Search results for "Fas"
showing 10 items of 2015 documents
Cosmology in a certain vector-tensor theory of gravitation
2014
We study relevant cosmological topics in the framework of a certain vector-tensor theory of gravitation (hereafter VT). This theory is first compared with the so-called extended electromagnetism (EE). These theories have a notable resemblance and both explain the existence of a cosmological constant. It is shown that, in EE, a positive dark energy density requires a Lagrangian leading to quantum ghosts, whereas VT is free from these ghosts. On account of this fact, the remainder of the paper is devoted to study cosmology in the framework of VT. Initial conditions, at high redshift, are used to solve the evolution equations of all the VT scalar modes. In particular, a certain scalar mode cha…
Transient absorption of polarons in KNbO3
2002
Abstract Transient absorption spectra have been measured in a number of undoped KNbO 3 crystals following two kinds of electronic excitation: two-photon absorption of 200 fs laser pulses and 10 ns pulsed electron beam. A band peaking at 0.8 eV and broad, poorly resolved absorption in the range 1.3–3.3 eV were observed. Based on similarity to the 1 eV band in LiNbO 3 previously identified as the intrinsic electron polaron (electron self-localized on niobium in the regular lattice site), we suggest that the transient absorption band at 0.8 eV in KNbO 3 is also associated with the intrinsic electron polaron.
New ALICE detectors for Run 3 and 4 at the CERN LHC
2020
Abstract Run 3 at the CERN LHC is scheduled to start in March 2021. In preparation for this new data taking period the ALICE experiment is making major modifications to its subsystems and is introducing three new detectors: the new Inner Tracking System, the Muon Forward Tracker, and the Fast Interaction Trigger. The new detectors will enhance tracking, especially at low transverse momenta, improve vertexing, provide the required triggering, fast timing, luminosity, and forward multiplicity functionality. For instance, it will be possible to measure beauty from displaced J/ ψ vertices down to transverse momenta p T ∼ 0 and improve precision for the ψ (2S) measurements. The upgraded ALICE wi…
Kalman filter tracking and vertexing in a silicon detector for neutrino physics
2002
Abstract This article describes the application of Kalman filter techniques for the tracking and vertexing of particles inside the NOMAD-STAR detector, a silicon vertex detector installed in NOMAD, one of the neutrino oscillation experiments at the CERN-SPS. The use of the Kalman filter simplifies computationally the tracking and vertex procedure for NOMAD-STAR. The alignment of NOMAD-STAR is shown as an example of the application of the Kalman filter for tracking purposes. The accuracy of the method is such that one obtains alignment residuals between 9 and 12 μm . Furthermore, a preliminary measure of the impact parameter (with an RMS ∼36 μm ) illustrates the vertexing capabilities of thi…
Optical investigations of TlBr detector crystals
2004
Shift of fundamental absorption edge, the position of main luminescence bands, the luminescence decay and transient absorption spectra in three TlBr crystals were studied. The γ-quanta detector made from TlBr crystals with similar transient absorption and luminescence parameters shows similar detector properties. The iodine impurity in TlBr was detected by optical methods. The role of impurities and crystal defects in γ-quanta detectors manufactured is discussed.
Accurate Fission Data for Nuclear Safety
2013
The Accurate fission data for nuclear safety (AlFONS) project aims at high precision measurements of fission yields, using the renewed IGISOL mass separator facility in combination with a new high current light ion cyclotron at the University of Jyvaskyla. The 30 MeV proton beam will be used to create fast and thermal neutron spectra for the study of neutron induced fission yields. Thanks to a series of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a mass resolving power in the order of a few hundred thousands. In this paper we present the experimental setup and the design of a neutron converter target for IGISOL. The goal is to have a flexi…
Application of ultra-fast timing techniques to the study of exotic and weakly produced nuclei
2005
Ultra-fast time-delayed techniques have been recently applied in a number of studies where exotic nuclei were identified using advanced selection techniques. These include large Compton-suppressed Ge arrays, in-flight separators or recoil separators. Some of the new results are discussed in this presentation. Besides the results for $^{32}$Mg and $^{96}$Pd, they include the first determination of the half-life of the $8^+$ state in $^{80}$Ge, $T_1/2$ = 2.95(6) ns, and significantly more precise results for $^{51}$Mn (3680 keV level) and $^{48}$V (421 keV level), $T_1/2$ = 1760(40) ps and $T_1/2$ $\leq$ 135 ps, respectively. Development of new scintillators will steadily improve precision an…
Development of a laser ion source at IGISOL
2005
FURIOS, the Fast Universal laser IOn Source, is under development at the IGISOL (Ion Guide Isotope Separator On-Line) mass separator facility in Jyvaskyla, Finland. This new laser ion source will combine a state-of-the-art solid state laser system together with a dye laser system, for the selective and efficient production of exotic radioactive species without compromising the universality and fast release inherent in the IGISOL system. The motivation for, and development of, this ion source is discussed in relation to the programme of research ongoing at this mass separator facility.
ULTRA-FAST FLASH OBSERVATORY (UFFO) FOR OBSERVATION OF EARLY PHOTONS FROM GAMMA RAY BURSTS
2013
I.H. Park, S. Ahmad, P. Barrillon, S. Brandt, C. Budtz-Jorgensen, A.J. Castro-Tirado, P. Chen, Y.J. Choi, P. Connell, S. Dagoret-Campagne, C. Eyles, B. Grossan, M.–H.A. Huang, A. Jung, S. Jeong, J.E. Kim, M.B. Kim, S.-W. Kim, Y.W. Kim, A.S. Krasnov, J. Lee, H. Lim, E.V. Linder, T.–C. Liu, N. Lund, K.W. Min, G.W. Na, J.W. Nam, M.I. Panasyuk, J. Ripa, V. Reglero, J.M. Rodrigo, G.F. Smoot, J.E. Suh, S. Svertilov, N. Vedenkin, M.–Z. Wang, I. Yashin Ewha Womans University, Seoul, Korea University of Paris-Sud 11, Orsay, France Technical University of Denmark, Copenhagen, Denmark Instituto de Astrofisica de Andalucia CSIC, Granada, Spain National Taiwan University, Taipei, Taiwan Korea Advanced I…
One-shot color digital holography based on the fractional talbot effect
2010
We present a simple method for recording on-axis color digital holograms in a single shot. Our system performs parallel phase-shifting interferometry by using the fractional Talbot effect for every chromatic channel simultaneously. Experimental results are also shown.