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Nuclear physicists measure properties of the rarest element on Earth

Nuclear physicists at the ISOLDE radioactive-beam facility at CERN, including a number from the universities of York and Manchester, have for the first time measured the radioactive properties of astatine, the rarest element on earth.

This new study fills a long-standing gap in the periodic table; astatine, atomic number 85, is the last element present in nature for which this fundamental property remained unknown. The element is of particular interest because isotopes of astatine are candidates for the creation of radiopharmaceuticals for cancer treatment by targeted alpha therapy.

This research, co-funded by the UK’s Science and Technology Facilities Council (STFC) and published today in the journal Nature Communications, could help chemists to develop applications for astatine in radiotherapy, as well as developing theories that predict the structure of super-heavy elements. UK researchers working on the project included Professor Andrei Andreyev from the University of York and Dr Bruce Marsh from CERN and the University of Manchester.

By looking at the ionization potential of astatine, that is the energy needed to remove one electron from the atom and thereby turning it into an ion, this international team of scientists , have been able to understand more about the chemical reactivity of astatine and the stability of its chemical bonds in compounds.

Astatine occurs naturally in only trace amounts on Earth, less than 28 grams (1 oz) exist at any one time, but physicists at ISOLDE can make artificial isotopes of astatine by bombarding uranium targets with high-energy protons. By shining a series of precisely wavelength-tuned lasers at the astatine atoms, the team that operates the resonance ionization laser ion source (RILIS) at ISOLDE measured the ionization potential of astatine to be 9.31751 electron volts.

Dr. Marsh said:

"None of the many short-lived isotopes used in medicine exist in nature; they have to be artificially produced by nuclear reactions. The possible medical isotopes of astatine are not so different in this respect. What is different about astatine is that its scarcity in nature makes it difficult to study by experiment, which is why this measurement of one of the fundamental properties is a significant achievement."

Professor Andreyev noted that:

“The experimental value for astatine also serves for benchmarking theories that predict the atomic and chemical properties of super-heavy elements, in particular a recently discovered element 117, which shares very similar characteristics to astatine.”

UK access to CERN is funded by STFC.

View the full story at the CERN website at

Further information

Measurement of the first ionization potential of astatine by laser ionization spectroscopy, 14 May, Nature Communications.

It will be available later at


Images of the ISOLDE facility are available on request.


To speak with or contact Bruce Marsh please contact:

Wendy Ellison
STFC Press Officer
Tel: 01925 603232
Mob: 07919 548012

About CERN

CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel and Serbia are associate members in the pre-stage to membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have observer status.

The On-Line Isotope Mass Separator ISOLDE is a facility dedicated to the production of a large variety of radioactive ion beams for many different experiments in the fields of nuclear and atomic physics, solid-state physics, materials science and life sciences. The facility is located at the Proton-Synchrotron Booster (PSB) of the European Organisation for Nuclear Research CERN. It is operated by the ISOLDE Collaboration, whose present members are: Belgium, CERN, Denmark, Finland, France, Germany, Greece, India, Ireland, Italy, Norway, Romania, Spain, Sweden and the United Kingdom.


The Science and Technology Facilities Council is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security.

The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.

STFC operates or hosts world class experimental facilities including in the UK the ISIS pulsed neutron source, the Central Laser Facility, and LOFAR, and is also the majority shareholder in Diamond Light Source Ltd.

It enables UK researchers to access leading international science facilities by funding membership of international bodies including European Laboratory for Particle Physics (CERN), the Institut Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the European Southern Observatory (ESO). STFC is one of seven publicly-funded research councils. It is an independent, non-departmental public body of the Department for Business, Innovation and Skills (BIS).

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