972 research outputs found
MCHIT - Monte Carlo model for proton and heavy-ion therapy
We study the propagation of nucleons and nuclei in tissue-like media within a
Monte Carlo Model for Heavy-ion Therapy (MCHIT) based on the GEANT4 toolkit
(version 8.2). The model takes into account fragmentation of projectile nuclei
and secondary interactions of produced nuclear fragments. Model predictions are
validated with available experimental data obtained for water and PMMA phantoms
irradiated by monoenergetic carbon-ion beams. The MCHIT model describes well
(1) the depth-dose distributions in water and PMMA, (2) the doses measured for
fragments of certain charge, (3) the distributions of positron emitting nuclear
fragments produced by carbon-ion beams, and (4) the energy spectra of secondary
neutrons measured at different angles to the beam direction. Radial dose
profiles for primary nuclei and for different projectile fragments are
calculated and discussed as possible input for evaluation of biological dose
distributions. It is shown that at the periphery of the transverse dose profile
close to the Bragg peak the dose from secondary nuclear fragments is comparable
to the dose from primary nuclei.Comment: Talk given at International Conference on Nuclear Data for Science
and Technology ND-2007, Nice, France, April 22-27, 200
Nuclear resonance fluorescence of Pb in heavy-ion colliders
In ultraperipheral collisions (UPC) of nuclei the impact of
Lorentz-contracted electromagnetic fields of collision partners leads to their
excitations. In case of heavy nuclei the emission of neutrons is a main
deexcitation channel and forward neutrons emitted in UPC were detected at the
Relativistic Heavy-Ion Collider (RHIC) and at the Large Hadron Collider (LHC)
by means of Zero Degree Calorimeters. However, the excitation of low-lying
discrete nuclear states is also possible in UPC below the neutron separation
energy. In this work by means of the Weizsacker-Williams method the data on
nuclear resonance fluorescence (NRF) induced by real photons in 208 Pb are used
to model the excitations of discrete levels in colliding nuclei. Due to Lorentz
boosts one can expect that deexcitation photons with energies up to 40 GeV and
300 GeV are emitted in very forward direction, respectively, at the LHC and at
the Future Circular Collider (FCC-hh). Energy, rapidity and angular
distributions of such photons are calculated in the laboratory system, which
can be used for monitoring of collider luminosity or triggering particle
production in UPC.Comment: 7 pages, 5 figures, 1 table, calculations for FCC-hh has been added
in figure
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