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Author  |
Wuensch, W.; Degiovanni, A.; Calatroni, S.; Korsback, A.; Djurabekova, F.; Rajamaki, R.; Giner-Navarro, J. |
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Title |
Statistics of vacuum breakdown in the high-gradient and low-rate regime |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review Accelerators and Beams |
Abbreviated Journal |
Phys. Rev. Accel. Beams |
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Volume |
20 |
Issue |
1 |
Pages |
011007 - 11pp |
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Abstract |
In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DCto 12GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments. |
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Address |
[Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio] CERN, European Org Nucl Res, CH-1211 Geneva, Switzerland, Email: anders.korsback@helsinki.fi |
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Amer Physical Soc |
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English |
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ISSN |
2469-9888 |
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Conference |
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Notes |
WOS:000400781300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3125 |
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Author |
Woolley, B.; Burt, G.; Dexter, A.C.; Peacock, R.; Millar, W.L.; Catalan Lasheras, N.; Degiovanni, A.; Grudiev, A.; Mcmonagle, G.; Syratchev, I.; Wuensch, W.; Rodriguez Castro, E.; Giner Navarro, J. |
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Title |
High-gradient behavior of a dipole-mode rf structure |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review Accelerators and Beams |
Abbreviated Journal |
Phys. Rev. Accel. Beams |
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Volume |
23 |
Issue |
12 |
Pages |
122002 - 11pp |
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Keywords |
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Abstract |
A normal-conducting, X-band traveling wave structure operating in the dipole mode has been systematically high-gradient tested to gain insight into the maximum possible gradients in these types of structure. Measured structure conditioning, breakdown behavior, and achieved surface fields are reported as well as a postmortem analysis of the breakdown position and a scanning electron microscope analysis of the high-field surfaces. The results of these measurements are then compared to high-gradient results from monopole-mode cavities. Scaled to a breakdown rate of 10(-6), the cavities were found to operate at a peak electric field of 154 MV/m and a peak modified Poynting vector S-c of 5.48 MW/mm(2). The study provides important input for the further development of dipole-mode cavities for use in the Compact Linear Collider as a crab cavity and dipole-mode cavities for use in x-ray free-electron lasers as well as for studies of the fundamental processes in vacuum arcs. Of particular relevance are the unique field patterns in dipole cavities compared to monopole cavities, where the electric and magnetic fields peak in orthogonal planes, which allow the separation of the role of electric and magnetic fields in breakdown via postmortem damage observation. The azimuthal variation of breakdown crater density is measured and is fitted to sinusoidal functions. The best fit is a power law fit of exponent 6. This is significant, as it shows how breakdown probability varies over a surface area with a varying electric field after conditioning to a given peak field. |
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Address |
[Woolley, B.; Burt, G.; Dexter, A. C.; Peacock, R.; Millar, W. L.] Univ Lancaster, Lancaster LA1 4YW, England |
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Amer Physical Soc |
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English |
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Edition |
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ISSN |
2469-9888 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000614886300002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4696 |
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Author |
Warnecke, S.; Sevryuk, M.B.; Ceperley, D.M.; Toennies, J.P.; Guardiola, R.; Navarro, J. |
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Title |
The structure of para-hydrogen clusters |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal D |
Abbreviated Journal |
Eur. Phys. J. D |
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Volume |
56 |
Issue |
3 |
Pages |
353-358 |
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Keywords |
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Abstract |
The path integral Monte Carlo calculated radial distributions of para-hydrogen clusters (p-H-2) N consisting of N = 4-40 molecules interacting via a Lennard-Jones potential at T = 1.5 K show evidence for additional peaks compared to radial distributions calculated by diffusion Monte Carlo (T = 0 K) and path integral Monte Carlo at T <= 0.5 K. The difference in structures is attributed to quantum delocalization at the lowest temperature. The new structures at finite temperatures appear to be consistent with classical structures calculated for an effective Morse potential, which in order to account for the large zero point energy, is substantially softer than the Lennard-Jones potential. |
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Address |
[Warnecke, S.; Sevryuk, M. B.; Toennies, J. P.] Max Planck Inst Dynam & Self Org, D-37073 Gottingen, Germany, Email: navarro@ific.uv.es |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Language |
English |
Summary Language |
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Series Volume |
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Edition |
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ISSN |
1434-6060 |
ISBN |
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Notes |
ISI:000274327600008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
505 |
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Author |
Pi, M.; Barranco, M.; Navarro, J.; Ancilotto, F. |
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Title |
Nucleation and cavitation in parahydrogen |
Type |
Journal Article |
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Year |
2012 |
Publication |
Chemical Physics |
Abbreviated Journal |
Chem. Phys. |
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Volume |
399 |
Issue |
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Pages |
213-217 |
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Keywords |
Nucleation; Cavitation; Metastable phases; Liquid parahydrogen |
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Abstract |
We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model. |
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Address |
[Pi, Marti; Barranco, Manuel] Univ Barcelona, Fac Fis, Dept ECM, E-08028 Barcelona, Spain, Email: marti@ecm.ub.es |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0301-0104 |
ISBN |
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Medium |
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Expedition |
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Conference |
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Notes |
WOS:000304196100027 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1039 |
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Author |
Pastore, A.; Tarpanov, D.; Davesne, D.; Navarro, J. |
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Title |
Spurious finite-size instabilities in nuclear energy density functionals: Spin channel |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
92 |
Issue |
2 |
Pages |
024305 - 9pp |
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Keywords |
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Abstract |
Background: It has been recently shown that some Skyrme functionals can lead to nonconverging results in the calculation of some properties of atomic nuclei. A previous study has pointed out a possible link between these convergence problems and the appearance of finite-size instabilities in symmetric nuclear matter (SNM) around saturation density. Purpose: We show that the finite-size instabilities not only affect the ground-state properties of atomic nuclei, but they can also influence the calculations of vibrational excited states in finite nuclei. Method: We perform systematic fully-self consistent random phase approximation (RPA) calculations in spherical doubly magic nuclei. We employ several Skyrme functionals and vary the isoscalar and isovector coupling constants of the time-odd term s . Delta s. We determine critical values of these coupling constants beyond which the RPA calculations do not converge because the RPA stability matrix becomes nonpositive. Results: By comparing the RPA calculations of atomic nuclei with those performed for SNM we establish a correspondence between the critical densities in the infinite system and the critical coupling constants for which the RPA calculations do not converge. Conclusions: We find a quantitative stability criterion to detect finite-size instabilities related to the spin s . Delta s term of a functional. This criterion could be easily implemented in the standard fitting protocols to fix the coupling constants of the Skyrme functional. |
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Address |
[Pastore, A.] CEA, DAM, DIF, F-91297 Arpajon, France |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000358933500007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2320 |
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Author |
Pastore, A.; Martini, M.; Davesne, D.; Navarro, J.; Goriely, S.; Chamel, N. |
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Title |
Linear response theory and neutrino mean free path using Brussels-Montreal Skyrme functionals |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
90 |
Issue |
2 |
Pages |
025804 - 11pp |
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Keywords |
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Abstract |
The Brussels-Montreal Skyrme functionals have been successful in describing properties of both finite nuclei and infinite homogeneous nuclear matter. In their latest version, these functionals have been equipped with two extra density-dependent terms in order to reproduce simultaneously ground state properties of nuclei and infinite nuclear matter properties while avoiding at the same time the arising of ferromagnetic instabilities. In the present article, we extend our previous results of the linear response theory to include such extra terms at both zero and finite temperature in pure neutron matter. The resulting formalism is then applied to derive the neutrino mean free path. The predictions from the Brussels-Montreal Skyrme functionals are compared with ab initio methods. |
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Address |
[Pastore, A.; Martini, M.; Goriely, S.; Chamel, N.] Univ Libre Brussels, Inst Astron & Astrophys, B-1050 Brussels, Belgium |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000341027800009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1901 |
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| Permanent link to this record |
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Author |
Pastore, A.; Davesne, D.; Navarro, J. |
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Title |
Nuclear matter response function with a central plus tensor Landau interaction |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of Physics G |
Abbreviated Journal |
J. Phys. G |
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Volume |
41 |
Issue |
5 |
Pages |
055103 - 17pp |
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Keywords |
Landau; random phase approximation; phenomenological interactions; tensor |
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Abstract |
We present a method to obtain response functions in the random phase approximation (RPA) based on a residual interaction described in terms of Landau parameters with central plus tensor contributions. The response functions keep the explicit momentum dependence of the RPA, in contrast with the traditional Landau approximation. Results for symmetric nuclear matter and pure neutron matter are presented using Landau parameters derived from finite-range interactions, both phenomenological and microscopic. We study the convergence of response functions as the number of Landau parameters is increased. |
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Address |
[Pastore, A.; Navarro, J.] Univ Libre Brussels, Inst Astron & Astrophys, B-1050 Brussels, Belgium, Email: apastore@ulb.ac.be |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0954-3899 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000334662500015 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1750 |
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| Permanent link to this record |
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Author |
Pastore, A.; Davesne, D.; Navarro, J. |
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Title |
Linear response of homogeneous nuclear matter with energy density functionals |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physics Reports |
Abbreviated Journal |
Phys. Rep. |
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Volume |
563 |
Issue |
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Pages |
1-67 |
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Keywords |
Skyrme functional; Linear response theory; Landau parameters |
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Abstract |
Response functions of infinite nuclear matter with arbitrary isospin asymmetry are studied in the framework of the random phase approximation. The residual interaction is derived from a general nuclear Skyrme energy density functional. Besides the usual central, spin-orbit and tensor terms it could also include other components as new density-dependent terms or three-body terms. Algebraic expressions for the response functions are obtained from the Bethe-Salpeter equation for the particle-hole propagator. Applications to symmetric nuclear matter, pure neutron matter and asymmetric nuclear matter are presented and discussed. Spin-isospin strength functions are analyzed for varying conditions of density, momentum transfer, isospin asymmetry, and temperature for some representative Skyrme functionals. Particular attention is paid to the discussion of instabilities, either real or unphysical, which could manifest in finite nuclei. |
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Address |
[Pastore, A.] Univ Libre Bruxelles, Inst Astron & Astrophys, B-1050 Brussels, Belgium, Email: davesne@ipnl.in2p3.fr |
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Corporate Author |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-1573 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000350515400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2143 |
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| Permanent link to this record |
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Author |
Navarro, J.; Polls, A. |
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Title |
Spin instabilities of infinite nuclear matter and effective tensor interactions |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
87 |
Issue |
4 |
Pages |
044329 - 11pp |
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Keywords |
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Abstract |
We study the effects of the tensor force, present in modern effective nucleon-nucleon interactions, in the spin instability of nuclear and neutron matter. Stability conditions of the system against certain very low energy excitation modes are expressed in terms of Landau parameters. It is shown that in the spin case, the stability conditions are equivalent to the condition derived from the spin susceptibility, which is obtained as the zero-frequency and long-wavelength limit of the spin response function calculated in the random phase approximation. Zero-range forces of the Skyrme type and finite-range forces of M3Y and Gogny type are analyzed. It is shown that for the Skyrme forces considered, the tensor effects are sizable and tend to increase the spin instability, which appears at smaller densities than in the case that the tensor is not taken into account. On the contrary, the tensor contribution of finite-range forces to the spin susceptibility is small or negligible for both isospin channels of symmetric nuclear matter as well as for neutron matter. A comparison with the spin susceptibility provided by realistic interactions is also presented. |
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Address |
Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000317866200005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1408 |
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Author |
Navarro, J.; Mateo, D.; Barranco, M.; Sarsa, A. |
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Title |
Mg impurity in helium droplets |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of Chemical Physics |
Abbreviated Journal |
J. Chem. Phys. |
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Volume |
136 |
Issue |
5 |
Pages |
054301 - 9pp |
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Keywords |
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Abstract |
Within the diffusion Monte Carlo approach, we have determined the structure of isotopically pure and mixed helium droplets doped with one magnesium atom. For pure He-4 clusters, our results confirm those of Mella et al. [J. Chem. Phys. 123, 054328 (2005)1 that the impurity experiences a transition from a surface to a bulk location as the number of helium atoms in the droplet increases. Contrarily, for pure He-3 clusters Mg resides in the bulk of the droplet due to the smaller surface tension of this isotope. Results for mixed droplets are presented. We have also obtained the absorption spectrum of Mg around the 3s3p P-1(1) <- 3s(2) S-1(0) transition. |
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Address |
[Sarsa, A.] Univ Cordoba, Dept Fis, Fac Ciencias, E-14071 Cordoba, Spain, Email: fa1sarua@uco.es |
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Publisher |
Amer Inst Physics |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-9606 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000300547200018 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
921 |
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