255 research outputs found
Analytical approximations of the Lindhard equations describing radiation effects
Starting from the general Lindhard theory describing the partition of
particles energy in materials between ionisation and displacements, analytical
approximate solutions have been derived, for media containing one and more
atomic species, for particles identical and different to the medium ones.
Particular cases, and the limits of these equations at very high energies are
discussed.Comment: 10 pages, 5 figures, latex2e, submitted to Nucl. Instr. Meth. in
Phys. Res.
The influence of initial impurities and irradiation conditions on defect production and annealing in silicon for particle detectors
Silicon detectors in particle physics experiments at the new accelerators or
in space missions for physics goals will be exposed to extreme radiation
conditions. The principal obstacles to long-term operation in these
environments are the changes in detector parameters, consequence of the
modifications in material properties after irradiation. The phenomenological
model developed in the present paper is able to explain quantitatively, without
free parameters, the production of primary defects in silicon after particle
irradiation and their evolution toward equilibrium, for a large range of
generation rates of primary defects. Vacancy-interstitial annihilation,
interstitial migration to sinks, divacancy and vacancy-impurity complex (VP,
VO, V2O, CiOi and CiCs) formation are taken into account. The effects of
different initial impurity concentrations of phosphorus, oxygen and carbon, as
well as of irradiation conditions are systematically studied. The correlation
between the rate of defect production, the temperature and the time evolution
of defect concentrations is also investigated.Comment: 14 pages, 8 figures, submitted to Nucl. Instrum. Meth. Phys. Res.
Annealing of radiation induced defects in silicon in a simplified phenomenological model
The concentration of primary radiation induced defects has been previously
estimated considering both the explicit mechanisms of the primary interaction
between the incoming particle and the nuclei of the semiconductor lattice, and
the recoil energy partition between ionisation and displacements, in the frame
of the Lindhard theory. The primary displacement defects are vacancies and
interstitials, that are essentially unstable in silicon. They interact via
migration, recombination, annihilation or produce other defects. In the present
work, the time evolution of the concentration of defects induced by pions in
medium and high resistivity silicon for detectors is modelled, after
irradiation. In some approximations, the differential equations representing
the time evolution processes could be decoupled. The theoretical equations so
obtained are solved analytically in some particular cases, with one free
parameter, for a wide range of particle fluences and/or for a wide energy range
of the incident particles, for different temperatures; the corresponding
stationary solutions are also presented.Comment: 14 pages, 5 figures, accepted to Nuclear Instruments and Methods in
Physics Research B second version, major revisio
Theoretical calculations of the primary defects induced by pions and protons in SiC
In the present work, the bulk degradation of SiC in hadron (pion and proton)
fields, in the energy range between 100 MeV and 10 GeV, is characterised
theoretically by means of the concentration of primary defects per unit
fluence. The results are compared to the similar ones corresponding to diamond,
silicon and GaAs.Comment: 9 pages, 2 figures, in press to Nuclear Instruments and Methods in
Physics Research A v2 - modified title, and major revision
Diamond degradation in hadron fields
The energy dependence of the concentration of primary displacements induced
by protons and pions in diamond has been calculated in the energy range 50 MeV
- 50 GeV, in the frame of the Lindhard theory. The concentrations of primary
displacements induced by protons and pions have completely different energy
dependencies: the proton degradation is very important at low energies, and is
higher than the pion one in the whole energy range investigated, with the
exception of the delta33 resonance region. Diamond has been found,
theoretically, to be one order of magnitude more resistant to proton and pion
irradiation in respect to silicon.Comment: 7 pages, 3 figure
Comparative Energy Dependence of Proton and Pion Degradation in Diamond
A comparative theoretical study of the damages produced by protons and pions,
in the energy range 50 MeV - 50 GeV, in diamond, is presented. The
concentration of primary defects (CPD) induced by hadron irradiation is used to
describe material degradation. The CPD has very different behaviours for
protons and pions: the proton degradation is important at low energies and is
higher than the pion one in the whole energy range investigated, with the
exception of the Delta33 resonance region, where a large maximum of the
degradation exists for pions. In comparison with silicon, the most investigated
and the most studied material for detectors, diamond theoretically proves to be
one order of magnitude more resistant, both to proton and pion irradiation.Comment: 7 pages, 5 figure
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