Ikeno, N., Kimura, R., Yamagata-Sekihara, J., Nagahiro, H., Jido, D., Itahashi, K., et al. (2011). Precision Spectroscopy of Deeply Bound Pionic Atoms and Partial Restoration of Chiral Symmetry in Medium. Prog. Theor. Phys., 126(3), 483–509.
Abstract: We study theoretically the formation spectra of deeply bound pionic atoms expected to be observed by experiments with high energy resolution at RIBF/RIKEN, and we discuss in detail the possibilities to extract new information on the pion properties at finite density from the observed spectra, which may provide information on partial restoration of chiral symmetry in medium. We find that the non-yrast pionic states such as 2s are expected to be seen in the (d,(3)He) spectra, which will be helpful to reduce uncertainties of the theoretical calculations in the neutron wave functions in nucleus. The observation of the 2s state with the ground is state is also helpful to reduce the experimental uncertainties associated in the calibration of the absolute excitation energy. We find that the nuclear densities probed by atomic pions are quite stable and almost constant for various atomic states and various nuclei. Effects of the pion wave function renormalization to the formation spectra are also evaluated.
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Borexino Collaboration(Bellini, G. et al), & Pena-Garay, C. (2011). Precision Measurement of the (7)Be Solar Neutrino Interaction Rate in Borexino. Phys. Rev. Lett., 107(14), 141302–5pp.
Abstract: The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0 +/- 1.5(stat)(-1.6)(+1.5)(syst)counts/(day . 100 ton). This corresponds to a nu(e)-equivalent (7)Be solar neutrino flux of (3.10 +/- 0.15) x 10(9) cm(-2) s(-1) and, under the assumption of nu(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51 +/- 0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 sigma. A global solar neutrino analysis with free fluxes determines Phi(pp) = 6.06(-0.66)(+0.02) x 10(10) cm(-2) s(-1) and Phi(CNO) < 1.3 x 10(9) cm(-2) s(-1) (95% C.L.). These results significantly improve the precision with which the Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.
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HADES Collaboration(Agakishiev, G. et al), Diaz, J., & Gil, A. (2011). pp and pi pi intensity interferometry in collisions of Ar+KCl at 1.76A GeV. Eur. Phys. J. A, 47(5), 63–8pp.
Abstract: Results on pp, pi(+) pi(+), and pi-pi-intensity interferometry are reported for collisions of Ar+KCl at 1.76A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The pp source radii are found significantly larger than the pp emission radius. The present radii do well complement the beam-energy dependences of Gaussian source radii of the collision system of size A + A similar or equal to 40 + 40. The pp source radius at fixed beam energy is found to increase linearly with the cube root of the number of participants. From this trend, a lower limit of the pp correlation radius is deduced.
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Fornengo, N., Lineros, R. A., Regis, M., & Taoso, M. (2011). Possibility of a Dark Matter Interpretation for the Excess in Isotropic Radio Emission Reported by ARCADE. Phys. Rev. Lett., 107(27), 271302–5pp.
Abstract: The ARCADE 2 Collaboration has recently measured an isotropic radio emission which is significantly brighter than the expected contributions from known extra-galactic sources. The simplest explanation of such excess involves a "new'' population of unresolved sources which become the most numerous at very low (observationally unreached) brightness. We investigate this scenario in terms of synchrotron radiation induced by weakly interacting massive particle (WIMP) annihilations or decays in extra-galactic halos. Intriguingly, for light-mass WIMPs with a thermal annihilation cross section, the level of expected radio emission matches the ARCADE observations.
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Carles, M., Lerche, C. W., Sanchez, F., Mora, F., & Benlloch, J. M. (2011). Position correction with depth of interaction information for a small animal PET system. Nucl. Instrum. Methods Phys. Res. A, 648, S176–S180.
Abstract: In this work we study the effects on the spatial resolution when depth of interaction (001) information is included in the parameterization of the line of response (LOR) for a small animal positron emission tomography (PET) system. One of the most important degrading factors for PET is the parallax error introduced in systems that do not provide DOI information of the recorded gamma-rays. Our group has designed a simple and inexpensive method for DOI determination in continuous scintillation crystals. This method is based, on one hand, in the correlation between the scintillation light distribution width in monolithic crystals and the DOI, and, on the other hand, on a small modification of the widely applied charge dividing circuits (CDR). In this work we present a new system calibration that includes the DOI information, and also the development of the correction equations that relates the LOR without and with DOI information. We report the results obtained for different measurements along the transaxial field of view (FOV) and the image quality enhancement achieved specially at the edge of the FOV.
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