6
S. Hilaire and S. Goriely
3 Nuclear Models for Nuclear Reactions
The three nuclear reaction models whose qualitative features have been discussed
above rely on various input data. The latter can either be directly measured or have
to be deduced from other models. Two types of approaches can be distinguished.
The first one, traditionally employed, is generally based on empirical expressions
which can be easily fine-tuned to reproduce data. The more recently developed ones
have benefited from the increase in computing power which enables today to provide
microscopic models able to compete with the traditional approaches.
3.1 Basic Nuclear Structure Information
The most fundamental data required for a nuclear reaction is the mass of the
various nuclei that can appear during a decay process. This knowledge is necessary
to determine reaction thresholds and to compute the kinematic relations enabling
laboratory to centre of mass frame transformations. Other quantities such as
nucleus levels’ excitation energies, spins and parities are also welcome and govern
features such as angular distribution or decay selection rules. Another feature also
interesting though not mandatory is the deformed or spherical nature of the target.
This information is particularly useful to adopt the proper treatment of the OM.
Experimental nuclear masses are available today for nearly 2500 nuclei [1]. This
set constitutes the reference data that nuclear mass models try to reproduce at best.
Many different mass models have been developed during the last decades and the
most advanced ones are able today to reach a root mean square (rms) deviation
from experiment close to 500 keV [2], a remarkable level of accuracy with respect
to the mass of a nucleus of the order of a GeV. Generally speaking, the more the
nuclear mass models are based on first principle physics, the higher the predictive
power should be. This has been recently demonstrated by analysing the predictive
power of various mass models adjusted on the 2003 atomic mass evaluation [3]
with respect to the update of 2012 [4] and 2016 [1]. One of the big advantages of
the microscopic models is that on top of the nuclear masses, they can also provide
spectroscopic data, as well as all detailed input which can be used in other models,
thus improving the coherence in an attempt to predict microscopically a nuclear
reaction.
3.2 The Optical Model
The OM is very important since it determines the reaction cross section that the PE
and CN models are then going to spread in the different outgoing open channels. It
also provides the direct elastic, total and inelastic cross sections as well as various
S. Hilaire and S. Goriely
3 Nuclear Models for Nuclear Reactions
The three nuclear reaction models whose qualitative features have been discussed
above rely on various input data. The latter can either be directly measured or have
to be deduced from other models. Two types of approaches can be distinguished.
The first one, traditionally employed, is generally based on empirical expressions
which can be easily fine-tuned to reproduce data. The more recently developed ones
have benefited from the increase in computing power which enables today to provide
microscopic models able to compete with the traditional approaches.
3.1 Basic Nuclear Structure Information
The most fundamental data required for a nuclear reaction is the mass of the
various nuclei that can appear during a decay process. This knowledge is necessary
to determine reaction thresholds and to compute the kinematic relations enabling
laboratory to centre of mass frame transformations. Other quantities such as
nucleus levels’ excitation energies, spins and parities are also welcome and govern
features such as angular distribution or decay selection rules. Another feature also
interesting though not mandatory is the deformed or spherical nature of the target.
This information is particularly useful to adopt the proper treatment of the OM.
Experimental nuclear masses are available today for nearly 2500 nuclei [1]. This
set constitutes the reference data that nuclear mass models try to reproduce at best.
Many different mass models have been developed during the last decades and the
most advanced ones are able today to reach a root mean square (rms) deviation
from experiment close to 500 keV [2], a remarkable level of accuracy with respect
to the mass of a nucleus of the order of a GeV. Generally speaking, the more the
nuclear mass models are based on first principle physics, the higher the predictive
power should be. This has been recently demonstrated by analysing the predictive
power of various mass models adjusted on the 2003 atomic mass evaluation [3]
with respect to the update of 2012 [4] and 2016 [1]. One of the big advantages of
the microscopic models is that on top of the nuclear masses, they can also provide
spectroscopic data, as well as all detailed input which can be used in other models,
thus improving the coherence in an attempt to predict microscopically a nuclear
reaction.
3.2 The Optical Model
The OM is very important since it determines the reaction cross section that the PE
and CN models are then going to spread in the different outgoing open channels. It
also provides the direct elastic, total and inelastic cross sections as well as various