117747714
Study on multifractal structure of the distribution fluctuation of secondary particles in the core region of EAS
The differences of space distributions and time profiles between the gamma-ray and proton induced shower particles are studied using Monte Carlo simulation data. The multifractal analysis is performed with the G-moment method for the distribution fluctuation of secondary particles near the core of showers induced by gamma-rays and protons. From the spectrum functions of gamma and proton events, it is seen that this method can be adopted as a basis for the gamma/proton separation. It is shown that the separation of gamma and proton can be achieved with a good efficiency in the energy region of 1-10TeV.
122356247
Automatic analysis of the emulsion chamber using the image scanner applied to the Tibet hybrid experiment
A new method of emulsion chamber analysis by using an image scanner is developed in order to process a large number of X-ray films used in the Tibet hybrid experiment which is carried out to observe primary proton spectrum in the PeV region. The experimental procedure in this method consists of multiple steps of processing the image of the X-ray films, i.e. the detection of cascade showers induced by high-energy γ-rays, the noise reduction, the spatial reconstruction of γ-families and their energy determination. The quality of the results obtained by the new method is compared with that obtained by the current manual method or Monte Carlo simulations. It is shown that sufficiently high quality of the emulsion chamber analysis is realized by the automatic method both in energy and geometrical resolution.
118189735
Studies of neutron-rich nuclei with the CLARA-PRISMA setup and description of the heavy-ion detector DANTE
A polymeric antioxidant which comprises a monomeric unit having a formula (I): (I) wherein R1 is methyl or ethyl; and a monomeric unit having a formula (II): (II) which imparts an excellent resistance against heat- or light-aging to a synthetic fiber and a resin.
119301447
Calibration of pulse transit time through a cable for EAS experiments
In ground-based extensive air shower experiments, the direction and energy are reconstructed by measuring the relative arrival time of secondary particles, and the energy they deposit. The measurement precision of the arrival time is crucial for determination of the angular resolution. For this purpose, we need to obtain a precise relative time offset for each detector, and to apply the calibration process. The time offset is associated with the photomultiplier tube, cable, relevant electronic circuits, etc. In view of the transit time through long cables being heavily dependent on the ambient temperature, a real-time calibration method for the cable transit time is investigated in this paper. Even with a poor-resolution time-to-digital converter, this method can achieve high precision. This has been successfully demonstrated with the Front-End-Electronic board used in the Daya Bay neutrino experiment.
118454051
Investigation of excited states in $^{18}$Ne via resonant elastic scattering of $^{17}$F+p and its astrophysical implication in the stellar reaction of $^{14}$O($\alpha$,$p$)$^{17}$F
Properties of proton resonances in $^{18}$Ne have been investigated efficiently by utilizing a technique of proton resonant elastic scattering with a $^{17}$F radioactive ion (RI) beam and a thick proton target. A 4.22~MeV/nucleon $^{17}$F RI beam was produced via a projectile-fragmentation reaction, and subsequently separated by a Radioactive Ion Beam Line in Lanzhou ({\tt RIBLL}). Energy spectra of the recoiled protons were measured by two sets of $\Delta$E-E silicon telescope at center-of-mass scattering angles of $\theta_{c.m.}$$\approx$175${^\circ}$$\pm$5${^\circ}$, $\theta_{c.m.}$$\approx$152${^\circ}$$\pm$8${^\circ}$, respectively. Several proton resonances in $^{18}$Ne were observed, and their resonant parameters have been determined by an $R$-matrix analysis of the differential cross sections in combination with the previous results. The resonant parameters are related to the reaction-rate calculation of the stellar $^{14}$O($\alpha$,$p$)$^{17}$F reaction, which was thought to be the breakout reaction from the hot CNO cycles into the $rp$-process in x-ray bursters. Here, $J^\pi$=(3$^-$, 2$^-$) are tentatively assigned to the 6.15-MeV state which was thought the key 1$^-$ state previously. In addition, a doublet structure at 7.05 MeV are tentatively identified, and its contribution to the resonant reaction rate of $^{14}$O($\alpha$,$p$)$^{17}$F could be enhanced by at least factors of about 4$\sim$6 in comparison with the previous estimation involving only a singlet. The present calculated resonant rates are much larger than those previous values, and it may imply that this breakout reaction could play a crucial role under x-ray bursters conditions.
14865448
Performance of the RPCs for the ARGO detector operated at the YangBaJing laboratory (4300 m a.s.l.)
Bakelite RPCs, assembled according to the ARGO design, have been operated in the high altitude Laboratory of YBJ using dedicated electronics to pick-up the streamer signal. Here we report on the results concerning absorbed current, single counting rate, efficiency and time resolution. Environmental data concerning the operating temperature inside the ARGO experimental hall are also reported.
18650091
Search for Ambient Neutralino Dark Matter at Accelerator
We investigate the possibility of using accelarator beam particles to collide with the ambient neutralino dark matter particles in cosmic rays as a way to search for the cold dark matter. We study in detail its inelastic and elastic scattering with the projectile particles at electron-positron colliders and discuss the possible experimental signals and the relevent background.
119029021
CPT violating electrodynamics and Chern-Simons modified gravity
The electrodynamics with a Chern-Simons term p(mu)A(nu)(F) over tilde (mu nu) violates Lorentz and CPT symmetries with a non-vanishing p(mu). For a fixed vector p(mu), in this Letter we point out that the energy-momentum tensor of this theory coupled to the gravity minimally is symmetric but not divergence free, which consequently makes the gravitational field equation inconsistent. To preserve the consistency, we introduce a Chern-Simons term in the gravity sector with the coefficient determined by the Lorentz and CPT violating term in the electromagnetic field. Further we study the phenomenologies of the model oil the cosmic microwave background radiation and the relic gravitational waves. (C) 2009 Elsevier B.V. All rights reserved.
119362091
Adiabatic gravitational perturbation during reheating
We study the possibilities of parametric amplification of the gravitational perturbation during reheating in single-held inflation models. Our result shows that there is no additional growth of the super-horizon modes beyond the usual predictions.
14959007
Gravity in a model of multi-branes alternated between Minkowski and AdS spacetime in the fifth dimension
We construct in this Letter a multi-brane model with Minkowski and AdS spacetime alternated in the fifth dimension and study the gravity on the brane of our universe. We will show that in this model there are both the graviton-like resonant state which generates the "quasi-localized gravity" and the resonant states of the massive KK mode. This model gives rise to gravity which deviates from the Newton gravitational potential at small and large scale which, however can be shown to be consistent with the observations in the absence of fine-tuning of the model parameters. (C) 2002 Elsevier Science B.V. All rights reserved.
119454465
Possible Effects of Dark Energy on the Detection of Dark Matter Particles
We study in this paper the possible influence of the dark energy on the detection of the dark matter particles. In models of dark energy described by a dynamical scalar field such as the Quintessence, its interaction with the dark matter will cause the dark matter particles such as the neutralino vary as a function of space and time. Given a specific model of the Quintessence and its interaction in this paper we calculate numerically the corrections to the neutralino masses and the induced spectrum of the neutrinos from the annihilation of the neutralinos pairs in the core of the Sun. This study gives rise to a possibility of probing for dark energy in the experiments of detecting the dark matter particles.