Exciting Neutron-rich Nuclei
Doktorsavhandling, 2018

Atoms are the building blocks which make up our world. Their stability depends on the atomic nucleus, consisting of protons and neutrons.
Nuclei are complex many-body quantum mechanical systems governed by the nucleon-nucleon interaction. The complexity and the intricate nature of the nucleon-nucleon interaction so far prevented the description of all existing nuclei by a single model.
Furthermore, nuclei and nuclear reactions in stars and stellar explosions play a key role in astrophysics. This motivates experiments to improve our understanding of nuclei and their role in the cosmos.

In this thesis I present results from experiments in complete kinematics performed at the radioactive beam facilities RIKEN and GSI/FAIR. The focus is on the rst measurement of unbound states in 29Ne, that were studied using neutron knockout reactions from 30Ne.
The invariant-mass spectrum shows two peaks, one at around 0.5 MeV and another one at 1.3 MeV. Moreover, results from an overview experiment, investigating light neutron-rich nuclei, between 3 < Z < 10, are also presented.
The results cover protonremoval cross sections in boron and carbon, important for designing future experiments, and unbound states in 26F where the rst unbound states are observed at the relative energy 323 keV. Furthermore, the structure of the unbound nucleus 13Be, which is important for its bridging role between the bound 12Be and the Borromean halo nucleus 14Be, is studied. Also measurements on Coulomb dissociation of 20;21N and 18C are presented which allow to improve our understanding of r-process nucleosynthesis.

RIKEN

GSI

Unbound States

FAIR

R3B

Radioactive Beams

PJ, Origo, Fysikgården 2
Opponent: Senior Physicist, Adjunct Professor Daniel Bazin, NSCL, Michigan State University

Författare

Simon Lindberg

Fundamental fysik

Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

Physical Review C - Nuclear Physics,; Vol. 93(2016)

Artikel i vetenskaplig tidskrift

Effective proton-neutron interaction near the drip line from unbound states in F-25,F-26

Physical Review C,; Vol. 96(2017)

Artikel i vetenskaplig tidskrift

Coulomb dissociation of 20,21 N

Physical Review C - Nuclear Physics,; Vol. 93(2016)

Artikel i vetenskaplig tidskrift

Determination of the neutron-capture rate of C-17 for r-process nucleosynthesis

Physical Review C,; Vol. 95(2017)p. Article no 014613 -

Artikel i vetenskaplig tidskrift

Matter as we know it, is built up by atoms. Atoms consist of electrons
surrounding a nucleus, which in turn consists of protons and neutrons, sum-
marily called nucleons. The nucleus is very dense compared to the rest of
the nucleus and, hence, this is where the major part of the mass of atoms
is found. Most of the materials around us consists of stable nuclei, but the
majority of the nuclei which have been observed are unstable, and change
the number of protons and neutrons by radioactive decay. Why some nuclei
are stable and others are not is governed by the laws of quantum mechanics
and the interaction between nucleons.

To better understand the interaction between the nucleons, experiments
are performed to probe the properties of different nuclei. These experiments
often study barely bound nuclei. For nuclei with a very large ratio of neu-
trons to protons, we observe that models start to fail, which makes these
nuclei very interesting as they can be used to learn more about the interac-
tion between the nucleons. This is very challenging though, as these nuclei
are very short-lived. Hence they have to be produced in accelerator facilities
before they can be studied. Here, stable nuclei are accelerated to velocities
close to the speed of light before they are collided with other nuclei. In the
collisions, the interesting short-lived isotopes are created.
In this thesis, the results from different experiments are presented. The
main focus is on the first measurements of unbound states in a neutron-rich
neon isotope, but results from unbound states in neutron-rich fluorine and
beryllium isotopes are also reported. Information about these states tests
how well existing models work for these isotopes. Other results include new
information on the production of unstable boron and carbon isotopes and on
the probability for certain carbon and nitrogen isotopes to capture neutrons
in nuclear reactions. Such reactions are important for understanding how
elements are formed in cosmic explosions.

Ämneskategorier

Subatomär fysik

Fysik

Fundament

Grundläggande vetenskaper

ISBN

978-91-7597-764-5

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4445

Utgivare

Chalmers tekniska högskola

PJ, Origo, Fysikgården 2

Opponent: Senior Physicist, Adjunct Professor Daniel Bazin, NSCL, Michigan State University