The cosmological lithium problem

October 10, 2018, University of Seville
Chart of the first six isotopes. Credit: University of Seville

The international collaborative n_TOF, in which a group of University of Seville researchers participated, has made use of the unique capacities of three of the world's nuclear facilities to carry out a new experiment aimed at finding an explanation of the cosmological lithium problem. This problem is among the still unresolved questions of the current standard description of the Big Bang. The new experimental results, their theoretical interpretations and their implications have been published in Physical Review Letters.

Nuclear reactions responsible for the creation and destruction of atomic nuclei during the Big Bang are crucial in the determining the primordial abundance of lithium, the third (and last) chemical element formed during the very early phase of the creation of the universe. The standard models of the Big Bang predict an abundance of Li7, the main lithium isotope, three or four times more than that actually observed. Recently, at the n_TOF facility at CERN, researchers investigated the possibility of a channel that might be able to increase the destruction rate of the isotope Be7, the precursor of Li7, and therefore make the calculated and observed cosmological abundance of lithium compatible.

"Potentially, a neutron reaction channel might be able to resolve the cosmological lithium problem, which is one of the still unresolved aspects of the current standard description of the Big Bang," says University of Seville Professor José Manuel Quesada.

At the SINQ facility at PSI (Villigen Switzerland) the "uncut" material for use in the new experiment was separated. The material was then sent to the ISOLDE radioactive beam facility at CERN to produce a pure target with less than 0.1 milligrams of Be7, which was then sent to the n_TOF facility to be included in neutron measurements.

This is the first time that the two CERN facilities dedicated to nuclear physics experiments have carried out an experiment together, using the ISOLDE radioactive ion beam to produce the target necessary for an experiment at n_TOF using the neutron time-of-flight technique.

In a previous experiment at n_TOF, the effective section of the 7Be(n,a)4He reaction was measured in a wide range of energies, which allowed for the imposition of strict restrictions on one of the destruction mechanisms of isotope Be7 during the Big Bang. In this experiment, however, the reaction 7Be(n,p)7Li was measured, extending previously acquired data to a greater range of energies, allowing for the updating of the rate used in the calculations in the standard model of the Big Bang.

"Although the new data obtained from the experiments at n_TOF allow for the establishment of a much firmer basis for BBN calculations, the conclusion of this project is that neutron channels are not enough to resolve the cosmological problem. The scientific community has a challenge that will require additional efforts to resolve, and this will involve the fields of nuclear astrophysics, astronomic observations, non-standard cosmology and even new physics beyond the Standard Model of particle physics," the researchers write.

Explore further: Beryllium-7 atom helps to check inconsistencies in the Big Bang theory

More information: L. Damone et al, Be7(n,p)Li7 Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.042701

Related Stories

ISOLDE mints isotopes of chromium

July 6, 2018

CERN's nuclear physics facility, ISOLDE, has minted a new coin in its impressive collection of isotopes. The facility has forged neutron-rich isotopes of the element chromium for the first time, and in prodigious quantities. ...

Video: HIE-ISOLDE's phase 2 reaches completion

August 21, 2018

CERN's ISOLDE facility has been in operation for more than 50 years. It produces radioactive isotopes for studies of the structure of atomic nuclei and a variety of other purposes including medical applications. Now, Phase ...

Unresolved puzzles in exotic nuclei

March 27, 2018

Research into the origin of elements is still of great interest. Many unstable atomic nuclei live long enough to be able to serve as targets for further nuclear reactions—especially in hot environments like the interior ...

Recommended for you

Magic number colloidal clusters

December 14, 2018

Complexity in nature often results from self-assembly, and is considered particularly robust. Compact clusters of elemental particles can be shown to be of practical relevance, and are found in atomic nuclei, nanoparticles ...

Tangled magnetic fields power cosmic particle accelerators

December 13, 2018

Magnetic field lines tangled like spaghetti in a bowl might be behind the most powerful particle accelerators in the universe. That's the result of a new computational study by researchers from the Department of Energy's ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 10, 2018
'' the creation of the universe'' it is so deeply ingrained in us that the lapsus are all over the place.

Hopefully the person does not lose her job.... because the religion of ''spontaneous generation of highly complex structures'' is very powerful.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.