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Fig. 2 Cross-section of the p(12C,12N) reaction at T p =1100 MeV/N, θ=0 0 [3]. The σ TT , σ TL and σ T +ε.σ L functions are described with the help of the phenomenological model MAID2- 007 [4]. The differences between data and model are fitted by single width gaussians, at the masses of these resonances, previously determined on the basis of different experiments. No attempt is done to adjust any mass. Such procedure assumes no interference between background and resonances. The γp→π 0 p reaction The backward cross-sections of the structure functions of the γp→π 0 p reaction, were measured by the Hall A collaboration at four angles θ and at Q 2 =1 (GeV/c) 2 [5]. The angular variations of all three structure functions display continuous shapes for nearly all seven narrow structure masses, namely: M=1136 MeV, 1210 MeV, 1277 MeV, 1339 MeV, 1384 MeV, 1480 MeV and 1540 MeV. Only one distribution, corresponding to ζ TL function for M=1136 MeV, displays a not smooth shape. The improvement between data and final fits is noteworthy; indeed before the introduction of the narrow structure contributions, the experimental data have to be compared to the baseline. The mean χ 2 is reduced from 24 to 3.1. The γp→π + n reaction The γp→π + n reaction was measured at JLAB in Hall B, by the CLAS collaboration [6]. The crosssection of the three structure functions were extracted at four values of the momentum transfers: Q 2 =0.3, 0.4, 0.5, and 0.6 (GeV/c) 2 and ten angles from θ=7.5 0 up to 142.5 0 . Figure 3 shows a reduced sample of structure function data, after substraction of the corresponding MAID2007 calculated results[4]. No attempt to get a better adjustment by shifting the masses is done on the fits. A large improvement between data and theory is observed. Quantitatively the mean χ 2 , obtained on a large number of structure functions, is reduced from 55 until 9.3. The ζ TT structure functions of the γp→π + n reaction, contribute to a large part of the uncertainty on the previous χ 2 value. The extracted structure surfaces, exhibit rather smooth angular variations. Although the two discussed experiments, namely one pion photoproduction reaction on proton, were performed with another aim, therefore with a resolution not appropriate for the present study, we have shown that their analysis is essentially Figure 3. The reaction γp→π + n [6]. σ T +ε.σ L structure function, at Q 2 =0.3 (GeV/c) 2 for θ=52.5 0 insert (a), and θ=127.5 0 insert (b), σ TT structure function at Q 2 =0.3 (GeV /c) 2 and θ=97.5 0 , insert (c), σ TL structure function at Q 2 =0.4 (GeV/c) 2 and θ=67.5 0 insert (d) .The red lines are the final fit, the gaussians are shown as black lines. improved after introduction of narrow low mass baryonic structures. Indeed the description with MAID is sometimes more qualitative than quantitative. The difference between data and results from MAID calculations, exhibit narrow peaks. The entire range discussed here, can be described by structures at the masses extracted from previous experiments performed with hadrons and previous analysis. In conclusion, this work increases the experimental signatures for the excitation of low mass baryons, previously observed in different reactions. A large improvement is obtained in the description of the data by a fit which takes narrow structures into account by gaussians with pre-determined masses and with widths given by the experimental resolution. References: [1] B.Tatischeff and E. Tomasi-Gustafsson, arXiv:1002.2059v1[nucl-ex]. [2]C. Ellegaarde et al., Phys. Rev. Lett. 59, 974 (1987)] [3] M. Roy-Stephan et al. Nucl. Phys. A488, 187c (1988). [4] D. Drechsel, S.S. Kamalov, L. Tiator Unitary Isobar Model - MAID2007, Eur. Phys. J. A34 (2007) 69. [5] G. Laveissière et al., Phys. Rev. C69 (2004) 045203. [6] H. Egiyan et al. Phys. Rev. C73 (2006) 025204 45
The PVA4 parity violation experiment IPNO Participation: R. Kunne, M. Morlet, S. Ong, J. Van de Wiele Collaboration : IKP Mainz, LNS-MIT Cambridge Le but de l’expérience PVA4 est l’extraction de la contribution des quarks étranges aux facteurs de forme électrique et magnétique du nucléon. Pour se faire, on étudie la diffusion élastique d’électrons polarisés longitudinalement sur des protons. Les asymétries résultantes sont sensibles à l’interaction faible violant la parité. Les mesures comprennent des prises de données aux angles avant et arrière, avec des cibles à hydrogène et à deuterium liquides. L'ensemble des mesures permet la séparation des facteurs de forme étranges G s E et G s M , ainsi que le facteur de forme axiale G p A . L'augmentation de l'énergie de MAMI à 1500 MeV, donne accès à des valeurs plus élevées de Q 2 . Parity violation in electron scattering The PVA4 Collaboration at the MAMI accelerator in Mainz measures the parity violating asymmetry in the cross-section of elastic scattering of longitudinally polarized electrons off unpolarized protons. The contributions can be expressed in terms of the strange electric and magnetic form factors G s E and G s M. The asymmetry A PV in the cross-section of elastic scattering of right- and left-handed polarized electrons off unpolarized protons can be written (omitting radiative corrections) as a sum of three terms: A PV = kinematic factor *(A V + A S + A A ), where A V represents the asymmetry due to the vector coupling at the proton vertex without strangeness contribution, A S is the asymmetry arising from the strangeness contribution only and A A represents the asymmetry due to the axial coupling at the proton vertex. By measuring the asymmetry A PV , and using the known electromagnetic form factors of the nucleon to determine A V , it is possible to determine A S , assuming that A A is small. Subsequently a linear combination of G s E and G s M can be derived from A S . For a separate determination of G s E and G s M it is necessary to perform at least two measurements at the same momentum transfer Q 2 , but at different scattering angles. Finally the assumption that A A is small can be checked by a third measurement on a deuterium target at the same Q 2 . PVA4 aims at doing the complete separation using its own data, by performing all three measurements at a given Q 2 . Forward and backward angles The PVA4 experiment has two possible configurations. In the forward-scattering configuration the angles from 30-40° are covered and the experiment is sensitive to G s E + ŋ · G s M, where ŋ depends on Q 2 . In the backward-scattering configura- Fig. 1: The PVA4 detector in the backward configuration. tion, covering angles between 140 and 150° the experiment is mainly sensitive to G s M. The PVA4 collaboration performed two forward angle measurements at momentum transfers of 0.11 (GeV/c) 2 and 0.23 (GeV/c) 2 , while a third one at 0.60 (GeV/ c) 2 is currently under way. A backward-angle measurement at a momentum transfer of 0.23 (GeV/c) 2 has been performed as well. As A A is not negligible at backward angles, PVA4 performed also a measurement on a deuterium target at that momentum transfer. Experimental set-up The experiment is located at the MAMI accelerator of the Institut für Kernphysik in Mainz, Germany. An electron source produces a polarized electron beam with an average polarization of 80%. The electron beam intensity is 20 μA. The beam polarization is measured on a regular basis with a Møller polarimeter. During data taking the polarization is monitored with a transmission Compton polarimeter situated in the experimental hall before the main experiment. The electron spin is randomly 46
Page 1 and 2: EXOTIC NUCLEI STRUCTURE AND REACTIO
Page 3 and 4: in the spectra by analyzing their t
Page 5 and 6: were taken from ref. [5]. Concernin
Page 7 and 8: keV -ray with the particles and the
Page 9 and 10: the 605.9 keV line of the 74 Zn 2+
Page 11 and 12: Figure 2 a n d analysis. Figure 2 s
Page 13 and 14: ing particles was thus obtained by
Page 15 and 16: 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: Exotic low mass narrow baryons from
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 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 and 100:
Latent heat of the phase transition
Page 101 and 102:
Alpha-particle particle condensatio
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Fluo X: Deexcitation time measureme
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ENERGY AND ENVIRONMENT The increasi
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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
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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