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Figure 3: Ratio of in-medium to free cross section as function of the relative momentum q for equilibrium distribution function. We compare our frequencies and damping rates with the results of three recent experiments [Altmeyer et al., Phys. Rev. A 76, 033610 (2007); Wright et al., Phys. Rev. Lett. 99, 150403 (2007); Riedl et al., Phys. Rev. A 78, 053609 (2008)]. The main success of our model is that with the help of the mean field U we can reproduce the observed upwards shift of the quadrupole mode in the collisionless regime compared to the ideal gas result. However, in the cases where the frequencies and damping rates are dominated by collisions, the description of the data becomes worse if one uses the in-medium cross section instead of the free one: Because of the enhanced cross section, the relaxation time τ gets too short. As an example we show the results for the scissors mode in fig. 4. The data are from the experiment by Wright et al. [loc. cit.], where the trap frequencies in the x and y directions were ω x =2π·830Hz and ω y =2π·415Hz. In the hydrodynamic (τ→0) and collisionless (τ→∞) limits, the scissors mode gets undamped and approaches the limiting frequencies √(ω x 2 +ω y 2 )=2π·944Hz and ω x +ω y =2π·1245Hz, respectively. As can be seen from fig. 4, the results with the in-medium cross Figure 4: Frequency (top) and damping (bottom) of the scissors mode as a function of temperature. Figure 5: Quadrupole response of a gas of 10000 atoms with interaction strength k F a = -2 and temperature T = 0.4 ε F . section (red lines), especially the damping rates Γ, go too fast to the hydrodynamic limit at lower temperatures, i.e., the relaxation time is too small. Numerical solution of the Boltzmann equation The approximations which are implicitly made in the method of moments could be a possible reason for the disagreement between theory and experiment. This is why we developed a code for the numerical solution of the Boltzmann equation based on the pseudoparticle method. The principle is the same as in the usual codes for the simulation of heavy-ion collisions, but the practical problems are different because of the much larger number of particles in the trapped gas. As a first application of this code, we studied the collective quadrupole oscillation of the cloud in a spherical harmonic trap, without mean field and with the free cross section. In the hydrodynamic limit (τ→0), the quadrupole mode becomes undamped and approaches the frequency √2ω 0 , where ω 0 denotes the trap frequency. In the collisionless limit (τ→∞), the mode is undamped, too, but its frequency is higher and approaches 2ω 0 . In fig. 5 we show the response obtained from the pseudoparticle simulation (red), compared with the method of moments (blue). While the general behaviour is similar, the simulation gives a higher frequency than the method of moments. If we use the form of the response function from the method of moments, but consider τ as a fitting parameter, we can very well reproduce the result of the simulation (purple). The fitted relaxation time τ obtained in this way is significantly higher (by ~50%) than that obtained from the method of moments, and a similar increase of τ is found in the whole range of interaction strengths and temperatures. It seems that the method of moments systematically overestimates the effect of collisions. This is a very encouraging result, since, as mentioned above, the relaxation time obtained by the method of moments for realistic parameters and with the in-medium cross section was too short in comparison with experimental data. References: S. Chiacchiera, T. Lepers, D. Davesne, and M. Urban, Phys. Rev. A 79, 033613 (2009). 77
Exploring key unknown neutrino properties in astrophysical and cosmological environments IPNO Participation: C. Volpe, J. Gava, J. Kneller Collaboration : A.B. Balantekin (University of Wisconsin-Madison), G.C. McLaughlin (North State Carolina University), N. Jachowicz (U. Gent) La physique des neutrinos est un domaine en plein développement depuis la découverte du phénomène d’oscillation il y a dix ans. Des progrès considérables ont été obtenus sur notre connaissance des propriétés des neutrinos. Toutefois des questions essentielles restent ouvertes telles que la connaissance de la valeur absolue et de la hiérarchie de masse, la valeur du troisième angle de mélange, la nature des neutrinos de Majorana ou Dirac et l’existence possible de la violation de CP leptonique. Nous utilisons les neutrinos provenant de sources astrophysiques et de l’Univers primordiale pour explorer ces questions et apporter des stratégies complémentaires dans ces recherches. En particulier, nous venons d’établir dans quelles conditions ils peuvent y avoir des effets de violation de CP sur les flux des neutrinos dans les milieux et étudié l’impact. Une signature pour le troisième angle de mélange a aussi été proposée qui peut être utilisée dans les observatoires des supernovae actuels, comme Super-Kamiokande, ou en phase d’étude. Introduction A major progress in our knowledge of neutrino properties has been made in the last decade after the discovery of the neutrino oscillation phenomenon - neutrinos can change their flavour while travelling - in 1998 by the Super-Kamiokande collaboration, with an impact in various fields of physics from particle physics to astrophysics and cosmology. Neutrinos are so elusive that they can pass through extensive layers of matter to tell us what happens in the inner core of stars, such as our Sun. A huge amount of neutrinos is emitted during the gravitational collapse of massive stars called core-collapse supernovae. R. Davis, for the pioneering solar neutrino experiment, and M. Koshiba for the observation of neutrinos from the supernova 1987A have been awarded the Physics Nobel Prize in 2002, with R. Giacconi. Neutrino oscillations turn out to be essential when neutrinos propagate in these and other astrophysical environments, including accretion-disks around blackholes, as well as in the early Universe, at the epoch of the synthesis of light elements. Neutrino physics is entering a crucial phase. In the coming years several experiments will address crucial open issues, among which the third neutrino mixing angle value, the neutrino (Majorana versus Dirac) nature, the neutrino mass scale and hierarchy, and the possible existence of CP violation in the lepton sector. Neutrinos from massive stars or the Early Universe can bring essential information on these open questions, either from searching their effects in these environments (on the r-process or Big-Bang Nucleosythesis for example) or in observations in detectors on Earth. This is one of the strategies followed by the theoretical group working on neutrinos at IPN Important results have been obtained in the last two years concerning both the value of the third neutrino mixing angle and CP violation. Searching for indirect effects of leptonic CP violation in core-collapse supernovae and the Early Universe (BBN epoch) We have investigated neutrino propation including the coupling with matter at tree level (MSW effect) and a non-zero CP violating Dirac phase [1]. We have identified, for the first time, the conditions under which there can be CP violating effects in supernovae. Any physics that breaks the equality among the muon and tau neutrino fluxes at the neutrinosphere, such as loop corrections or physics beyond the standard model (ex. flavourchanging-neutral-currents), engenders CP effects on the neutrino fluxes and on observables. One of our main goals has also been to determine whether CP violation can have an impact on the r- process. Unraveling the site and the conditions for the r-process is one of the most important open questions in nuclear astrophysics, core-collapse supernovae being one of the possible sites. However present simulations are unable to reproduce the observed abundances because (anti)neutrino interactions with neutrons and protons reduce the available neutrons. In such a context effects of several percent, such as those that might arise from CP violation, can be important. Our results show that the CP effects on the neutron/proton ratio -- a key parameter for the r-process -- are less than 1% within the MSW framework [1,3]. In [2] we have generalized these results to the case where the neutrino-neutrino interaction is also included. Following the neutrino evolution in matter in this case becomes much more demanding because a large number of stiff non-linear differential equations are involved. We have shown that our demonstration holds also in the case where neutrino-neutrino interaction is included; and we have quantified the CP effects on the neutrino fluxes in the star. These turn out again to be of the order of several percent [2,3]. 78
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EXOTIC NUCLEI STRUCTURE AND REACTIO
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in the spectra by analyzing their t
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were taken from ref. [5]. Concernin
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keV -ray with the particles and the
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the 605.9 keV line of the 74 Zn 2+
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Figure 2 a n d analysis. Figure 2 s
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ing particles was thus obtained by
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First p-p p collisions in the ALICE
Page 17 and 18: Quarkonia physics with ALICE IPNO P
Page 19 and 20: NA50 updated puzzle IPNO Participat
Page 21 and 22: Status of the HADES experiment (I):
Page 23 and 24: Status of the HADES experiments (II
Page 25 and 26: Status of the HADES experiment (III
Page 27 and 28: Hadron physics in pbar-p p annihila
Page 29 and 30: Hadron Electrodynamics IPNO Partici
Page 31 and 32: G0 experiment at Jefferson Lab. IPN
Page 33 and 34: GEp-III and GEp-2 at Jefferson Lab
Page 35 and 36: Exotic low mass narrow baryons from
Page 37 and 38: The PVA4 parity violation experimen
Page 39 and 40: Etude des Distributions de Partons
Page 41 and 42: Latest Results from GRAAL IPNO Part
Page 43 and 44: Persistence of the Polarization in
Page 45 and 46: The northern site of the Pierre Aug
Page 47 and 48: The Pierre Auger southern Observato
Page 49 and 50: In figure 4 we plot the differentia
Page 51 and 52: THEORETICAL PHYSICS Research in the
Page 53 and 54: transfer reaction, the 34 Si(d, 3 H
Page 55 and 56: Collective excitations with SKYRME
Page 57 and 58: Pairing and nuclear incompressibili
Page 59 and 60: Pairing properties in nuclei and in
Page 61 and 62: Evaporation-residue residue cross s
Page 63 and 64: Extending the VMI model: normal and
Page 65 and 66: Alpha particle condensation in nucl
Page 67: Collective Modes in Ultracold Trapp
Page 71 and 72: Relic astrophysical and cosmologica
Page 73 and 74: After a term by term Borel resummat
Page 75 and 76: Chiral expansions of the π 0 lifet
Page 77 and 78: IPNO Participation: H. Sazdjian Eff
Page 79 and 80: fer is used to extract f + (0). We
Page 81 and 82: cleon. The spectrum becomes strongl
Page 83 and 84: A pseudo Coulombian potential in D=
Page 85 and 86: The many-body problem with an energ
Page 87 and 88: The rotational spectrum and the att
Page 89 and 90: Z-identification of very heavy nucl
Page 91 and 92: The Pegase project, a new solid sur
Page 93 and 94: But at 80 keV total energy ( 200 eV
Page 95 and 96: Isospin effects on fragment and par
Page 97 and 98: Radial collective energy and fragme
Page 99 and 100: Latent heat of the phase transition
Page 101 and 102: Alpha-particle particle condensatio
Page 103 and 104: Fluo X: Deexcitation time measureme
Page 105 and 106: ENERGY AND ENVIRONMENT The increasi
Page 107 and 108: toe/cap/y which energy access inequ
Page 109 and 110: nides. A global comparison can be p
Page 111 and 112: 3D coupling of Monte-Carlo neutroni
Page 113 and 114: Fission cross sections of actinides
Page 115 and 116: Studies and synthesis of specific m
Page 117 and 118: Chemistry and Electrochemistry of T
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function of temperature. The recent
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global electron number of the redox
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(D 0 /D)-1 ln complexes of Pa(V). I
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