Stopping cross-section for protons across different phases of water

Fuente: arXiv
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Autores principales: Matias, F., Koval, N. E., de Vera, P., Garcia-Molina, R., Abril, I., Shorto, J. M. B., Yoriyaz, H., Pereira, J. J. N., Silva, T. F., Tabacniks, M. H., Vos, M., Grande, P. L.
Formato: Preprint
Publicado: 2025
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author Matias, F.
Koval, N. E.
de Vera, P.
Garcia-Molina, R.
Abril, I.
Shorto, J. M. B.
Yoriyaz, H.
Pereira, J. J. N.
Silva, T. F.
Tabacniks, M. H.
Vos, M.
Grande, P. L.
author_facet Matias, F.
Koval, N. E.
de Vera, P.
Garcia-Molina, R.
Abril, I.
Shorto, J. M. B.
Yoriyaz, H.
Pereira, J. J. N.
Silva, T. F.
Tabacniks, M. H.
Vos, M.
Grande, P. L.
contents Accurately quantifying the energy loss rate of proton beams in liquid water is crucial for the precise application and improvement of proton therapy, whereas the slowing down of proton in water ices also plays an important role in astrophysics. However, precisely determining the electronic stopping power, particularly for the liquid phase, has been elusive so far. Experimental techniques are difficult to apply to volatile liquids, and the availability of sufficient reliable measurements has been limited to the solid and vapor phases. The accuracy of current models is typically limited to proton energies just above the energy-loss maximum, making it difficult to predict radiation effects at an energy range of special relevance. We elucidate the phase differences in proton energy loss in water in a wide energy range (0.001-10 MeV) by means of real-time time-dependent density functional theory combined with the Penn method. This non-perturbative model, more computationally-efficient than current approaches, describes the phase effects in water in excellent agreement with available experimental data, revealing clear deviations around the maximum of the stopping power curve and below. As an important outcome, our calculations reveal that proton stopping quantities of liquid water and amorphous ice are identical, in agreement with recent similar observations for low-energy electrons, pointing out to this equivalence for all charged particles. This could help to overcome the limitation in obtaining reliable experimental information for the biologically-relevant liquid water target.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23396
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Stopping cross-section for protons across different phases of water
Matias, F.
Koval, N. E.
de Vera, P.
Garcia-Molina, R.
Abril, I.
Shorto, J. M. B.
Yoriyaz, H.
Pereira, J. J. N.
Silva, T. F.
Tabacniks, M. H.
Vos, M.
Grande, P. L.
Medical Physics
Accurately quantifying the energy loss rate of proton beams in liquid water is crucial for the precise application and improvement of proton therapy, whereas the slowing down of proton in water ices also plays an important role in astrophysics. However, precisely determining the electronic stopping power, particularly for the liquid phase, has been elusive so far. Experimental techniques are difficult to apply to volatile liquids, and the availability of sufficient reliable measurements has been limited to the solid and vapor phases. The accuracy of current models is typically limited to proton energies just above the energy-loss maximum, making it difficult to predict radiation effects at an energy range of special relevance. We elucidate the phase differences in proton energy loss in water in a wide energy range (0.001-10 MeV) by means of real-time time-dependent density functional theory combined with the Penn method. This non-perturbative model, more computationally-efficient than current approaches, describes the phase effects in water in excellent agreement with available experimental data, revealing clear deviations around the maximum of the stopping power curve and below. As an important outcome, our calculations reveal that proton stopping quantities of liquid water and amorphous ice are identical, in agreement with recent similar observations for low-energy electrons, pointing out to this equivalence for all charged particles. This could help to overcome the limitation in obtaining reliable experimental information for the biologically-relevant liquid water target.
title Stopping cross-section for protons across different phases of water
topic Medical Physics
url https://arxiv.org/abs/2505.23396