3,983 research outputs found
Semileptonic KL Decays at NA48
Preliminary results on KL->pi e nu(gamma) decays collected by the NA48
detector at the CERN SPS are reported. Using a sample of 6.8 X 10^6
reconstructed events BR(Ke3) = 0.4010+-0.0028+-0.0035 was obtained. From the
branching ratio the value of |Vus|= 0.2187+-0.0028 was extracted. The same data
sample has provided also a high precision measurement of the slope lambda+ of
the form factor of the Ke3 decay. Investigating the Ke3gamma decay, from a
sample of 18977 reconstructed events, BR(Ke3gamma)/BR(Ke3) =
(0.964+-0.008+0.012-0.011)% was determined.Comment: 4 pages, 2 figures. To appear in the proceedings of the Vth
Rencontres du Vietnam, Particle Physics and Astrophysics, Hanoi, Vietnam,
August 5-11, 200
A study of nuclear effects in interactions with the NOMAD detector
Nuclear effects in \numucc interactions with carbon nuclei have been studied
by using backward going protons and .
Detailed analyses, of the momentum distributions and of the production rates,
have been carried out in order to understand the mechanism producing these
particles. The backward proton data have been compared with the predictions of
the reinteraction and the short range correlation models.Comment: 8 pages, 7 figures, to be published in Proc. of NUINT01, The First
International Workshop on Neutrino-Nucleus Interactions in the Few GeV
Region; December 13-16 2001, KEK Tsukuba, Japa
NA48 Results on Kaon and Hyperon Decays Relevant to |V_us|
New results from the NA48 experiment on kaon and hyperon decays relevant to
|V_us| are reported here. For charged kaons we present measurements of BR(K+-
-> pi0 e+- nu) and BR(K+- -> pi0 mu+- nu). On neutral kaon decays we report the
measurements of BR(K_L -> pi+ pi-) and of K_L -> pi+- mu-+ nu form factors
slopes. For hyperons we present results on the BR(Xi0 -> Sigma+ e- nu_e).Comment: 4 pages, 3 figures, to appear in the proceedings of CKM 2006, 4th
International Workshop on the CKM Unitarity Triangle, December 12-16, 2006
Nagoya, Japa
Laser-Accelerated proton beams as diagnostics for cultural heritage
This paper introduces the first use of laser-generated proton beams as diagnostic for materials of interest in the domain of Cultural Heritage. Using laser-accelerated protons, as generated by interaction of a high-power short-pulse laser with a solid target, we can produce proton-induced X-ray emission spectroscopies (PIXE). By correctly tuning the proton flux on the sample, we are able to perform the PIXE in a single shot without provoking more damage to the sample than conventional methodologies. We verify this by experimentally irradiating materials of interest in the Cultural Heritage with laser-accelerated protons and measuring the PIXE emission. The morphological and chemical analysis of the sample before and after irradiation are compared in order to assess the damage provoked to the artifact. Montecarlo simulations confirm that the temperature in the sample stays safely below the melting point. Compared to conventional diagnostic methodologies, laser-driven PIXE has the advantage of being potentially quicker and more efficien
Design and optimization of a laser-PIXE beamline for material science applications
Multi-MeV proton beams can be generated by irradiating thin solid foils with ultra-intense (>10^18 W/cm^2) short laser pulses. Several of their characteristics, such as high bunch charge and short pulse duration, make them a complementary alternative to conventional radio frequency-based accelerators. A potential material science application is the chemical analysis of cultural heritage (CH) artifacts. The complete chemistry of the bulk material (ceramics, metals) can be retrieved through sophisticated nuclear techniques such as particle-induced X-ray emission (PIXE). Recently, the use of laser-generated proton beams was introduced as diagnostics in material science (laser-PIXE or laser-driven PIXE): Coupling laser-generated proton sources to conventional beam steering devices successfully enhances the capture and transport of the laser-accelerated beam. This leads to a reduction of the high divergence and broad energy spread at the source. The design of our hybrid beamline is composed of an energy selector, followed by permanent quadrupole magnets aiming for better control and manipulation of the final proton beam parameters. This allows tailoring both, mean proton energy and spot sizes, yet keeping the system compact. We performed a theoretical study optimizing a beamline for laser-PIXE applications. Our design enables monochromatizing the beam and shaping its final spot size. We obtain spot sizes ranging between a fraction of mm up to cm scale at a fraction of nC proton charge per shot. These results pave the way for a versatile and tunable laserPIXE at a multi-Hz repetition rate using modern commercially available laser systems
Laser-Generated Proton Beams for High-Precision Ultra-Fast Crystal Synthesis
We present a method for the synthesis of micro-crystals and micro-structured surfaces using laseraccelerated
protons. In this method, a solid surface material having a low melting temperature is
irradiated with very-short laser-generated protons, provoking in the ablation process thermodynamic
conditions that are between the boiling and the critical point. The intense and very quick proton energy
deposition (in the ns range) induces an explosive boiling and produces microcrystals that nucleate in a
plasma plume composed by ions and atoms detached from the laser-irradiated surface. The synthesized
particles in the plasma plume are then deposited onto a cold neighboring, non-irradiated, solid
secondary surface. We experimentally verify the synthesizing methods by depositing low-meltingmaterial
microcrystals - such as gold - onto nearby silver surfaces and modeling the proton/matter
interaction via a Monte Carlo code, confrming that we are in the above described thermodynamic
conditions. Morphological and crystallinity measurements indicate the formation of gold octahedral
crystals with dimensions around 1.2 μm, uniformly distributed onto a silver surface with dimensions
in the tens of mm2. This laser-accelerated particle based synthesis method paves the way for the
development of new material synthesis using ultrashort laser-accelerated particle beams
Thermal ablation and systemic therapies in the metastatic liver: time for a "glocal" approach
AFM and pulsed laser ablation methods for Cultural Heritage: application to archeometric analysis of stone artifacts
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