The Nuclear Structure of Exotic Fission Fragments
Lead Research Organisation:
University of Manchester
Department Name: Physics and Astronomy
Abstract
At the heart of the atom lies the atomic nucleus, an object so minute that it would take tens of billions laid end-to-end to make up the width of a human hair. The nucleus is itself composed of even smaller particles called neutrons and protons. The neutrons, as the name suggests, carry no electrical charge while the protons have a positive charge. Thus, the total number of protons in a nucleus determines the nuclear charge and is denoted by Z, the atomic number. It is this net positive charge that enables negatively-charged electrons to 'stick' to the nucleus to make neutral atoms. The electric forces within the nucleus try to push the protons apart and it is only the presence of the the strong, short-range attractive nuclear force between neutrons and protons that enables nuclei to exist in a stable state. The total number of neutrons and protons is called the mass number, A. Atomic nuclei are stable only for particular combinations of Z and A. If we try to make a nucleus with too many neutrons for a given number of protons it becomes unstable and tries to decay to products with lower total mass by a process known as beta decay. For very high atomic numbers the long-range electric repulsion between the protons becomes competitive to the nuclear attraction. These high-Z nuclei need proportionately more neutrons to protons than low-Z nuclei in order to be stable. Some high Z nuclei can be made to fission into two lighter nuclei with a large release of energy. The fission process results in products with roughly the same Z/A ratio as the parent nucleus. Since the parent is rich in neutrons, the products are also. Fission is therefore a natural way in which to produce unstable neutron-rich nuclei. Such nuclei are of great importance since they are used as stepping stones in the astrophysical rapid neutron-capture process that is the mechanism by which elements heavier than iron are made. Fission is also important in that it is currently the only way in which w
Organisations
Publications
A. G. {Smith} And C. E. {Barrett} And M. A. {Alothman}
(2010)
F}ission-fragment $\gamma$-ray angular correlations
A. G. {Smith} And I. {Tsekhanovich} And J. {Dare} And D. M. {Cullen} And B. J. {Varley} And N. {Lumley} And T. {Materna} And U. {Koster} And M. {Helmecke} And G. S. {Simpson}
(2008)
F}ission-{F}ragment {S}pectroscopy with {STEFF
Alastair Smith (Author)
(2012)
Fission-fragment spectroscopy with large arrays and STEFF
Colonna N
(2010)
Advanced nuclear energy systems and the need of accurate nuclear data: the n_TOF project at CERN
in Energy & Environmental Science
Czerwinski M
(2013)
Yrast excitations in the neutron-rich N = 52 isotones
in Physical Review C
Guerrero C
(2012)
Simultaneous measurement of neutron-induced capture and fission reactions at CERN
in The European Physical Journal A
Kurpeta J
(2012)
Low-spin structure of 85 Se and the ß n branching of 85 As
in Physical Review C
Kurpeta J
(2014)
Neutron configurations in Pd 113
in Physical Review C
Kurpeta J.
(2007)
Low-spin structure of
113Ru and
113Rh
in EUROPEAN PHYSICAL JOURNAL A
Ledoux X
(2014)
The Neutrons for Science Facility at SPIRAL-2
in Nuclear Data Sheets
Malkiewicz T
(2012)
Near-yrast structure of odd- A , neutron-rich Pr isotopes
in Physical Review C
Murray E
(2014)
Measurement of Gamma Energy Distributions and Multiplicities Using STEFF
in Nuclear Data Sheets
Orlandi R
(2006)
Single-particle and collective degrees of freedom in Zr 101 and Mo 103 , 105
in Physical Review C
Pinston J
(2006)
Triaxiality in Mo 105 and Mo 107 from the low to intermediate spin region
in Physical Review C
Pollitt A
(2012)
Gamma-ray multiplicity measurements using STEFF
in Journal of Physics: Conference Series
Rzaca-Urban T
(2013)
First observation of excited states in 87 Se: Collectivity and j - 1 anomaly at N = 53
in Physical Review C
Rzaca-Urban T
(2010)
Near-yrast structure of Pr 149
in Physical Review C
Rzaca-Urban T
(2011)
Near-yrast, medium-spin structure of Xe 143
in Physical Review C
Rzaca-Urban T
(2007)
First observation of medium-spin excitations in the 138Cs nucleus
in The European Physical Journal A
Rzaca-Urban T
(2007)
New excited states in Ge 82 : Possible weakening of the N = 50 closed shell
in Physical Review C
Rzaca-Urban T
(2009)
( h 11 / 2 , g 7 / 2 ) 9 - neutron excitation in Sr 92 , 94 , 96
in Physical Review C
Rzaca-Urban T
(2013)
Unexpected 5 / 2 - spin of the ground state in 147 Ba: No octupole deformation in ground states of odd- A Ba isotopes
in Physical Review C
Rzaca-Urban T
(2007)
First observation of excited states in the I 138 nucleus
in Physical Review C
Rzaca-Urban T
(2009)
Near-yrast structure of Cs 142 and Cs 144
in Physical Review C
Rzaca-Urban T
(2012)
Reflection symmetry of the near-yrast excitations in 145 Ba
in Physical Review C
Description | This grant has allowed the construction of a new fission-fragment spectrometer (STEFF) and it's commissioning at the ILL high-flux reactor in Grenoble. The key measurements are related to multiplicity and energy distributions of gamma rays emitted in neutron-induced fission at thermal energies. |
Exploitation Route | The STEFF spectrometer will now be used for a range of fission experiments. |
Sectors | Education,Energy |
Description | The gamma energy and multiplicity distributions will be used to advance the safety cases for new types of nuclear reactors. |
First Year Of Impact | 2006 |
Sector | Energy |
Impact Types | Societal,Economic |