exotic nuclei structure and reaction noyaux exotiques ... - IPN - IN2P3

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pattern is not trivially due to a change in the size of the quasi-projectile. After a shape analysis in the center of mass frame, only events with a total forward detected charge larger than 80% of the Au charge were considered.Two different procedures aiming at selecting events with negligible neck contribution were adopted. In the first one [6] (I) by eliminating events where the entrance channel dynamics induces a forward emission,in the quasi-projectile frame, of the heaviest fragment Z 1 .For isotropically decaying quasi-projectiles, this Figure 3: Size of the heaviest fragment Z 1 versus total excitation energy. That picture is constructed using the fit parameters extracted from the equivalent-canonical distribution. The distance between the two maxima, liquid and gas peaks, projected on the excitation energy axis corresponds to the latent heat of the transition. projectile selections. The results (for one quasiprojectile selection) are illustrated in figure 3. Figure 2: Upper part, measured distribution of the charge of the largest fragment normalized to the charge of the quasi-projectile detected in Au+Au collisions at three different bombarding energies. Lower part, weighted distributions obtained considering the same statistics for each excitation energy bin. procedure does not bias the event sample but only reduces the statistics. In a second strategy (II) the reduction of the neck contribution is obtained by keeping only ``compact'' events by imposing (i) an upper limit on the relative velocity among fragments, and (ii) a constant quasi-projectile size within 10% (see [7] for details). In both cases fission events were removed. The results obtained with the two different selection methods are shown in figure 2.To take into account the small variations of the source size, the charge of the heaviest fragment Z 1 has been normalized to the source size. After the weighting procedure (lower part of figure 2), a bimodal behavior of the largest fragment charge clearly emerges for both selection methods [8]. Those weighted experimental distributions can be fitted with an analytic function (see [8] for more details). From the obtained parameter values one can estimate the latent heat of the transition of the hot heavy nuclei studied (Z~70) as ΔE=8.1 ± 0.4 (stat) +1.2 -0.9 (syst) MeV per nucleon. Statistical error was derived from experimental statistics and systematic errors from the comparison between the two different quasi- References [1] P. Chomaz et al., Phys. Rev. E 64, 046114, 2001. [2] B. Borderie and M. F. Rivet, Prog. Part. Nucl. Phys. 61, 551, 2008. [3] D. H. E. Gross, World Scientific, Vol. 66 of World Scientific Lecture Notes in Physics, 2002. [4] F. Gulminelli, Nucl. Phys. A 791, 165 , 2007. [5] M. Di Toro et al., Eur. Phys. J A 30, 65, 2006. [6] M. Pichon et al. (INDRA Collaboration), Nucl. Phys. A 779, 267, 2006. [7] E. Bonnet et al. (INDRA and ALADIN Collaborations), Nucl. Phys. A, 1, 2009. [8] E. Bonnet et al. (INDRA and ALADIN Collaborations), Phys. Rev. Lett. 103, 072701, 2009. 109
Alpha-particle particle condensation in nuclear systems IPNO Participation: Ad. R. Raduta, B. Borderie, M. F. Rivet Collaboration : ISOSPIN Collaboration NIPNE, Bucharest Magurele, Romania LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France GANIL, CEA et CNRS/IN2P3, Caen, France IPN Lyon, Université Claude Bernard Lyon1, CNRS/IN2P3, Villeurbanne, France INFN, Sezione di Catania and Dipartimento di Fisica e Astronomia, Università di Catania, Italy INFN, Laboratori Nazionali del Sud and Dipartimento di Fisica e Astronomia, Saha Institute of Nuclear Physics, Kalkota, India La fragmentation de quasi-projectiles dans la réaction 40 Ca+ 12 C à 25 MeV par nucléon a été utilisée pour produire un état excité du 12 C (état de Hoyle) prédit théoriquement comme étant un état de condensation alpha. L’utilisation du multidétecteur CHIMERA à grande granularité couplé aux techniques de corrélation multi-particules a permis pour la première fois de mettre en évidence la condensation alpha en physique nucléaire. Introduction Bose-Einstein condensation (BEC) is known to occur in weakly and strongly interacting systems such as dilute gases [1] and 4 He liquid. For several years it has been considered that BEC may be formed in nuclear matter, as well. This hypothesis of a new phase of nuclear matter relies on the already known molecular-like structure of some light nuclei in both ground and excited states. Taking into account that the α-particle is characterized by the highest value of the binding energy per nucleon, it is straightforward to anticipate that the pre-formed nucleonic structure inside nuclei should be of α-type. This means that under some circumstances, the α-cluster Bose properties might dominate over the Fermi properties of the nucleus. Thus, by showing that the Hoyle state (i.e. the first excited state 0 + at 7.654 MeV of 12 C) and the sixth 0 + state at 15.097 MeV of 16 O are described by α-particle condensate type functions, reference [2] advances the idea that these states are candidates to observe α-condensation. A common feature of these states is their diluteness. Moreover, it is believed that these states are not unique and may occur in dilute Nα nuclei (up to N=10) whose excitation energies are close to the Nα-decay threshold [3]. In what regards the experimental results, the situation is much less advanced. The main explanation relies on the hardness to attain performances of the necessary apparatus. Taking into account that according to the present understanding, the compatibility of a nuclear state with α-particle condensation may be judged upon its excitation energy close to the Nα threshold, the emission simultaneity and both the low kinetic energy and kinetic energy dispersion, it becomes clear that probably the most appropriate methodology should involve high granularity-high solid angle particle detection, as Figure 1: α-α correlation function; the variable is the total kinetic of the two particles in their centerof-mass frame. neded in multifragmentation reactions [4]. The reaction 40 Ca+ 12 C studied with CHIMERA The nuclear reaction 40 Ca+ 12 C at 25 MeV per nucleon incident energy performed at LNS in Catania was studied. The beam impinging on a thin carbon target (320 μg/cm 2 ) was delivered by the Superconducting Cyclotron and the charged reaction products were detected by the CHIMERA 4π multidetector [5]. The beam intensity was kept constant at 10 7 ions/s to avoid pile-up events. CHIMERA consists of 1192 silicon-CsI(Tl) telescopes mounted on 35 rings covering 94% of the solid angle, with polar angle ranging from 1°to 176°. Among its most valuable characteristics, we mention the low detection and identification thresholds for light charged particles (LCP) and the very high granu- 110
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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
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Quarkonia physics with ALICE IPNO P
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NA50 updated puzzle IPNO Participat
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Status of the HADES experiment (I):
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Status of the HADES experiments (II
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Status of the HADES experiment (III
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Hadron physics in pbar-p p annihila
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Hadron Electrodynamics IPNO Partici
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G0 experiment at Jefferson Lab. IPN
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GEp-III and GEp-2 at Jefferson Lab
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Exotic low mass narrow baryons from
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The PVA4 parity violation experimen
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Etude des Distributions de Partons
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Latest Results from GRAAL IPNO Part
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Persistence of the Polarization in
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The northern site of the Pierre Aug
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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 and 68: Collective Modes in Ultracold Trapp
Page 69 and 70: Exploring key unknown neutrino prop
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: Latent heat of the phase transition
Page 103 and 104: Fluo X: Deexcitation time measureme
Page 105 and 106: ENERGY AND ENVIRONMENT The increasi
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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
Page 119 and 120: function of temperature. The recent
Page 121 and 122: global electron number of the redox
Page 123: (D 0 /D)-1 ln complexes of Pa(V). I
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