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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Vincent, A.C.; Fernandez Martinez, E.; Hernandez, P.; Mena, O.; Lattanzi, M. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Revisiting cosmological bounds on sterile neutrinos |
Type |
Journal Article |
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Year |
2015 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
04 |
Issue |
4 |
Pages |
006 - 23pp |
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Keywords |
particle physics – cosmology connection; cosmological neutrinos; cosmology of theories beyond the SM |
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Abstract |
We employ state-of-the art cosmological observables including supernova surveys and BAO information to provide constraints on the mass and mixing angle of a non-resonantly produced sterile neutrino species, showing that cosmology can effectively rule out sterile neutrinos which decay between BBN and the present day. The decoupling of an additional heavy neutrino species can modify the time dependence of the Universe's expansion between BBN and recombination and, in extreme cases, lead to an additional matter-dominated period; while this could naively lead to a younger Universe with a larger Hubble parameter, it could later be compensated by the extra radiation expected in the form of neutrinos from sterile decay. However, recombination-era observables including the Cosmic Microwave Background (CMB), the shift parameter R-CMB and the sound horizon r(s) from Baryon Acoustic Oscillations (BAO) severely constrain this scenario. We self-consistently include the full time-evolution of the coupled sterile neutrino and standard model sectors in an MCMC, showing that if decay occurs after BBN, the sterile neutrino is essentially bounded by the constraint sin(2) theta less than or similar to 0.026(m(s)/eV)(-2). |
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Address |
[Vincent, Aaron C.] Univ Durham, Dept Phys, IPPP, Durham DH1 3LE, England, Email: aaron.vincent@durham.ac.uk; |
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Iop Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Notes |
WOS:000355742500007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2261 |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Villanueva-Domingo, P.; Villaescusa-Navarro, F. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Removing Astrophysics in 21 cm Maps with Neural Networks |
Type |
Journal Article |
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Year |
2021 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
907 |
Issue |
1 |
Pages |
44 - 14pp |
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Keywords |
Cosmology; Cold dark matter; Dark matter; Dark matter distribution; H I line emission; Intergalactic medium; Cosmological evolution; Convolutional neural networks; Large-scale structure of the universe |
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Abstract |
Measuring temperature fluctuations in the 21 cm signal from the epoch of reionization and the cosmic dawn is one of the most promising ways to study the universe at high redshifts. Unfortunately, the 21 cm signal is affected by both cosmology and astrophysics processes in a nontrivial manner. We run a suite of 1000 numerical simulations with different values of the main astrophysical parameters. From these simulations we produce tens of thousands of 21 cm maps at redshifts 10 <= z <= 20. We train a convolutional neural network to remove the effects of astrophysics from the 21 cm maps and output maps of the underlying matter field. We show that our model is able to generate 2D matter fields not only that resemble the true ones visually but whose statistical properties agree with the true ones within a few percent down to scales 2 Mpc(-1). We demonstrate that our neural network retains astrophysical information that can be used to constrain the value of the astrophysical parameters. Finally, we use saliency maps to try to understand which features of the 21 cm maps the network is using in order to determine the value of the astrophysical parameters. |
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Address |
[Villanueva-Domingo, Pablo] Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, Apartado Correos 22085, E-46071 Valencia, Spain, Email: Pablo.Villanueva@ific.uv.es; |
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Iop Publishing Ltd |
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0004-637x |
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WOS:000612333400001 |
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no |
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yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4698 |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Villanueva-Domingo, P.; Gnedin, N.Y.; Mena, O. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Warm Dark Matter and Cosmic Reionization |
Type |
Journal Article |
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Year |
2018 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
852 |
Issue |
2 |
Pages |
139 - 7pp |
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Keywords |
cosmology: theory; galaxies: formation; intergalactic medium; large-scale structure of universe; methods: numerical |
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Abstract |
In models with dark matter made of particles with keV masses, such as a sterile neutrino, small-scale density perturbations are suppressed, delaying the period at which the lowest mass galaxies are formed and therefore shifting the reionization processes to later epochs. In this study, focusing on Warm Dark Matter (WDM) with masses close to its present lower bound, i.e., around the 3. keV region, we derive constraints from galaxy luminosity functions, the ionization history and the Gunn-Peterson effect. We show that even if star formation efficiency in the simulations is adjusted to match the observed UV galaxy luminosity functions in both CDM and WDM models, the full distribution of Gunn-Peterson optical depth retains the strong signature of delayed reionization in the WDM model. However, until the star formation and stellar feedback model used in modern galaxy formation simulations is constrained better, any conclusions on the nature of dark matter derived from reionization observables remain model-dependent. |
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Address |
[Villanueva-Domingo, Pablo; Mena, Olga] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, Apartado Correos 22085, E-46071 Valencia, Spain, Email: gnedin@fnal.gov |
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Iop Publishing Ltd |
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English |
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0004-637x |
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Notes |
WOS:000422865600009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3455 |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Villaescusa-Navarro, F.; Vogelsberger, M.; Viel, M.; Loeb, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Neutrino signatures on the high-transmission regions of the Lyman alpha forest |
Type |
Journal Article |
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Year |
2013 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
431 |
Issue |
4 |
Pages |
3670-3677 |
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Keywords |
neutrinos; intergalactic medium; quasars: absorption lines; cosmology: theory; large-scale structure of Universe |
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Abstract |
We quantify the impact of massive neutrinos on the statistics of low-density regions in the intergalactic medium as probed by the Lyman alpha forest at redshifts z = 2.2-4. Based on mock but realistic quasar (QSO) spectra extracted from hydrodynamic simulations with cold dark matter, baryons and neutrinos, we find that the probability distribution of weak Lyman alpha absorption features, as sampled by Lyman alpha flux regions at high transmissivity, is strongly affected by the presence of massive neutrinos. We show that systematic errors affecting the Lyman alpha forest reduce but do not erase the neutrino signal. Using the Fisher matrix formalism, we conclude that the sum of the neutrino masses can be measured, using the method proposed in this paper, with a precision smaller than 0.4 eV using a catalogue of 200 high-resolution (signal-to-noise ratio similar to 100) QSO spectra. This number reduces to 0.27 eV by making use of reasonable priors in the other parameters that also affect the statistics of the high-transitivity regions of the Lyman alpha forest. The constraints obtained with this method can be combined with independent bounds from the cosmic microwave background, large-scale structures and measurements of the matter power spectrum from the Lyman alpha forest to produce tighter upper limits on the sum of the masses of the neutrinos. |
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Address |
Univ Valencia, IFIC, CSIC, E-46071 Valencia, Spain, Email: viel@oats.inaf.it |
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Oxford Univ Press |
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English |
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0035-8711 |
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WOS:000319479000057 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1458 |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Vilella, E.; Alonso, O.; Trenado, J.; Vila, A.; Casanova, R.; Vos, M.; Garrido, L.; Dieguez, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
A test beam setup for the characterization of the Geiger-mode avalanche photodiode technology for particle tracking |
Type |
Journal Article |
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Year |
2012 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
694 |
Issue |
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Pages |
199-204 |
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Keywords |
The Geiger-mode avalanche photodiode (GAPD); CMOS; EUDET/AIDA telescope; Schottky detector; Test beam; Trigger logic unit (TLU) |
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Abstract |
It is well known that avalanche photodiodes operated in the Geiger mode above the breakdown voltage offer a virtually infinite gain and time accuracy in the picosecond range that can be used for single photon detection. However, their performance in particle detection still remains unexplored. In this contribution, we are going to expose different steps that we have taken in order to prove the efficiency of the Geiger mode avalanche photodiodes in the aforementioned field. In particular, we will present a setup for the characterization of these sensors in a test beam. The expected results of the test beam at DESY and CERN have been simulated with Geant4 and will also be exposed. |
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Address |
[Vilella, E.; Alonso, O.; Vila, A.; Casanova, R.; Dieguez, A.] Univ Barcelona, Dept Elect, E-08028 Barcelona, Spain, Email: evilella@el.ub.es |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0168-9002 |
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Notes |
WOS:000311020500029 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1256 |
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Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Vicente, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Higgs Lepton Flavor Violating Decays in Two Higgs Doublet Models |
Type |
Journal Article |
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Year |
2019 |
Publication |
Frontiers in Physics |
Abbreviated Journal |
Front. Physics |
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Volume |
7 |
Issue |
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Pages |
174 - 13pp |
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Keywords |
Higgs boson; lepton flavor violating decays; beyond the standard model; two Higgs doublet models; effective field theory |
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Abstract |
The discovery of a non-zero rate for a lepton flavor violating decay mode of the Higgs boson would definitely be an indication of New Physics. We review the prospects for such signal in Two Higgs Doublet Models, in particular for Higgs boson decays into tau μfinal states. We will show that this scenario contains all the necessary ingredients to provide large flavor violating rates and still be compatible with the stringent limits from direct searches and low-energy flavor experiments. |
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Address |
[Vicente, Avelino] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: avelino.vicente@ific.uv.es |
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Frontiers Media Sa |
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English |
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2296-424x |
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Notes |
WOS:000498568200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4206 |
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Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Valle, J.W.F. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Status and implications of neutrino masses: a brief panorama |
Type |
Journal Article |
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Year |
2015 |
Publication |
International Journal of Modern Physics A |
Abbreviated Journal |
Int. J. Mod. Phys. A |
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Volume |
30 |
Issue |
13 |
Pages |
1530034 - 13pp |
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Keywords |
Neutrino mixing and oscillations; seesaw mechanism; quark-lepton unification; flavor symmetry; electroweak symmetry breaking; neutrinoless double beta decay; dark matter; inflation |
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Abstract |
With the historic discovery of the Higgs boson our picutre of particle physics would have been complete were it nor for the neutrino sector and cosmology. I briefly discuss the role of neutrino masses and mixing upon gauge coupling unification, electroweak breaking and the flavor sector. Time is ripe for new discoveries such as leptonic CP violation, charged lepton flavor violation and neutrinoless double beta decay. Neutrinos could also play a role is elucidating the nature of dark matter and cosmic inflation. |
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Address |
Univ Valencia, CSIC, Inst Fis Corpuscular, E-46980 Valencia, Spain |
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Publisher |
World Scientific Publ Co Pte Ltd |
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English |
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ISSN |
0217-751x |
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Notes |
WOS:000353955400002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2211 |
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Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Valiente-Dobon, J.J. et al; Egea, J.; Huyuk, T.; Gadea, A.; Aliaga, R.; Jurado-Gomez, M.L.; Perez-Vidal, R.M. |
![find record details (via OpenURL) openurl](img/xref.gif)
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Title |
NEDA-NEutron Detector Array |
Type |
Journal Article |
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Year |
2019 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
927 |
Issue |
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Pages |
81-86 |
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Keywords |
NEDA; Nuclear structure; Gamma-ray spectroscopy; Neutron detector; Liquid scintillator; Digital electronics; Neutron-gamma discrimination |
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Abstract |
The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA. |
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Address |
[Valiente-Dobon, J. J.; Jaworski, G.; Goasduff, A.; Egea, J.; Modamio, V; de Angelis, G.; Bissiato, E.; Carturan, S.; Cocconi, P.; Conventi, D.; Deltoro, J. M.; Hadynska-Klekn, K.; Illan, A.; Raggio, A.; Siciliano, M.; Zanon, I] Ist Nazl Fis Nucl, Lab Nazl Legnaro, Legnaro, Italy, Email: valiente@lnl.infn.it |
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Elsevier Science Bv |
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English |
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0168-9002 |
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Notes |
WOS:000462142700010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3956 |
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Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Valdes-Cortez, C.; Niatsetski, Y.; Perez-Calatayud, J.; Ballester, F.; Vijande, J. |
![find record details (via OpenURL) openurl](img/xref.gif)
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Title |
A Monte Carlo study of the relative biological effectiveness in surface brachytherapy |
Type |
Journal Article |
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Year |
2022 |
Publication |
Medical Physics |
Abbreviated Journal |
Med. Phys. |
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Volume |
49 |
Issue |
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Pages |
5576-5588 |
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Keywords |
Monte Carlo; relative biological effectiveness; surface HDR brachytherapy |
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Abstract |
Purpose This work aims to simulate clustered DNA damage from ionizing radiation and estimate the relative biological effectiveness (RBE) for radionuclide (rBT)- and electronic (eBT)-based surface brachytherapy through a hybrid Monte Carlo (MC) approach, using realistic models of the sources and applicators. Methods Damage from ionizing radiation has been studied using the Monte Carlo Damage Simulation algorithm using as input the primary electron fluence simulated using a state-of-the-art MC code, PENELOPE-2018. Two Ir-192 rBT applicators, Valencia and Leipzig, one Co-60 source with a Freiburg Flap applicator (reference source), and two eBT systems, Esteya and INTRABEAM, have been included in this study implementing full realizations of their geometries as disclosed by the manufacturer. The role played by filtration and tube kilovoltage has also been addressed. Results For rBT, an RBE value of about 1.01 has been found for the applicators and phantoms considered. In the case of eBT, RBE values for the Esteya system show an almost constant RBE value of about 1.06 for all depths and materials. For INTRABEAM, variations in the range of 1.12-1.06 are reported depending on phantom composition and depth. Modifications in the Esteya system, filtration, and tube kilovoltage give rise to variations in the same range. Conclusions Current clinical practice does not incorporate biological effects in surface brachytherapy. Therefore, the same absorbed dose is administered to the patients independently on the particularities of the rBT or eBT system considered. The almost constant RBE values reported for rBT support that assumption regardless of the details of the patient geometry, the presence of a flattening filter in the applicator design, or even significant modifications in the photon energy spectra above 300 keV. That is not the case for eBT, where a clear dependence on the eBT system and the characteristics of the patient geometry are reported. A complete study specific for each eBT system, including detailed applicator characteristics (size, shape, filtering, among others) and common anatomical locations, should be performed before adopting an existing RBE value. |
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Address |
[Valdes-Cortez, Christian] Hosp Reg Antofagasta, Nucl Med Dept, Antofagasta, Chile, Email: cvalcort@gmail.com |
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Publisher |
Wiley |
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English |
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ISSN |
0094-2405 |
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Notes |
WOS:000811709400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5262 |
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Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Valdes-Cortez, C.; Mansour, I.; Rivard, M.J.; Ballester, F.; Mainegra-Hing, E.; Thomson, R.M.; Vijande, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
A study of Type B uncertainties associated with the photoelectric effect in low-energy Monte Carlo simulations |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
66 |
Issue |
10 |
Pages |
105014 - 14pp |
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Keywords |
Monte Carlo simulations; brachytherapy; low energy physics; photoelectric effect |
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Abstract |
Purpose. To estimate Type B uncertainties in absorbed-dose calculations arising from the different implementations in current state-of-the-art Monte Carlo (MC) codes of low-energy photon cross-sections (<200 keV). Methods. MC simulations are carried out using three codes widely used in the low-energy domain: PENELOPE-2018, EGSnrc, and MCNP. Three dosimetry-relevant quantities are considered: mass energy-absorption coefficients for water, air, graphite, and their respective ratios; absorbed dose; and photon-fluence spectra. The absorbed dose and the photon-fluence spectra are scored in a spherical water phantom of 15 cm radius. Benchmark simulations using similar cross-sections have been performed. The differences observed between these quantities when different cross-sections are considered are taken to be a good estimator for the corresponding Type B uncertainties. Results. A conservative Type B uncertainty for the absorbed dose (k = 2) of 1.2%-1.7% (<50 keV), 0.6%-1.2% (50-100 keV), and 0.3% (100-200 keV) is estimated. The photon-fluence spectrum does not present clinically relevant differences that merit considering additional Type B uncertainties except for energies below 25 keV, where a Type B uncertainty of 0.5% is obtained. Below 30 keV, mass energy-absorption coefficients show Type B uncertainties (k = 2) of about 1.5% (water and air), and 2% (graphite), diminishing in all materials for larger energies and reaching values about 1% (40-50 keV) and 0.5% (50-75 keV). With respect to their ratios, the only significant Type B uncertainties are observed in the case of the water-to-graphite ratio for energies below 30 keV, being about 0.7% (k = 2). Conclusions. In contrast with the intermediate (about 500 keV) or high (about 1 MeV) energy domains, Type B uncertainties due to the different cross-sections implementation cannot be considered subdominant with respect to Type A uncertainties or even to other sources of Type B uncertainties (tally volume averaging, manufacturing tolerances, etc). Therefore, the values reported here should be accommodated within the uncertainty budget in low-energy photon dosimetry studies. |
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Address |
[Valdes-Cortez, Christian; Ballester, Facundo; Vijande, Javier] Univ Valencia UV, Dept Fis Atom Mol & Nucl, Burjassot, Spain, Email: javier.vijande@uv.es |
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Iop Publishing Ltd |
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English |
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0031-9155 |
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WOS:000655291500001 |
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no |
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yes |
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yes |
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IFIC @ pastor @ |
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4847 |
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