1,240 research outputs found
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Large p/sub T/ production in 10/sup 4/-10/sup 7/ GeV interactions. [Parton and jet production models]
No full textEvidence for high transverse momentum in cosmic ray interactions is reviewed in the context of models with hard collisions of partons and jet production. Two types of experiments suggest significant production of secondaries with high p/sub T/ above 10/sup 4/ GeV. One compares the cosmic ray data to hard scattering models and discusses further analysis needed to distinguish such models from other possibilities for production of large transverse momentum
Gamma-ray production in supernova remnants
No full textThe bulk of cosmic rays of up to about 100 TeV are thought to be accelerated by the first-order Fermi mechanism at supernova shocks, producing a power-law spectrum. Both electrons and protons should be accelerated, but their ratio on acceleration is not well known. Recently, the EGRET instrument on the Compton Gamma Ray Observatory has observed supernova remnants IC 443 and γ Cygni at GeV energies. On the assumption that the observed γ-rays are produced by accelerated particles in the remnants (rather than, for example, from a central compact object), we model the contributions from pion production, bremsstrahlung, and inverse Compton scattering on the cosmic microwave, diffuse galactic, and locally produced radiation fields. In the case of the same spectral index for both electrons and nuclei and a cutoff at 80 TeV, we find that a spectral index of accelerated particles that is close to 2.4 and a ratio of electrons to protons in the range 0.2-0.3 give a good fit to the observed spectra. For lower cutoff energies, flatter spectra are possible. We also investigate the case in which the electron spectrum is steeper than that of nuclei. We discuss the implications of our results for observations at air shower energies, and for the propagation of cosmic rays.T. K. Gaisser, R. J. Protheroe, And Todor Stane
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Implications for new particle searches of some cosmic ray emulsion events. [Cross sections]
No full textCalculations of backgrounds for cosmic ray candidates for new particles in emulsions are summarized. Even if only the strongest cosmic ray candidates are accepted as genuine, the implication is that their production cross sections would be relatively large at accelerator energies (greater than or equal to 1..mu..b) and that decay modes with ..pi../sup 0/ appear to be prominent. Current accelerator upper bounds on sigma x B/sub K pi/ for production of hadrons with M greater than 2 GeV and the relation between these bounds and the cosmic ray events are discussed
Phenomenology of production of massive and new particles in hadronic interactions
No full textThe cross-sections for producing various heavy particles in hadronic collisions are related in a general framework which is first developed and then successfully applied to calculating the pp total inclusive cross-section up to 1500 GeV using the K/sup -/ inclusive cross- section as input, and also for computing Lambda production, the results being found to agree with recent Fermilab experiments. This framework is then applied to production of J, psi particles in hadronic collisions and a notable prediction is that the J, psi is produced along with another heavy particle. psi psi production is then calculated as a function of energy and compared to the recent BNL experiment while the total cross-section for pp to psi X at Fermilab energies (100 to 400 GeV) is predicted to be much larger than at BNL. Large cross-sections are predicted for production of possible heavy charmed hadrons at Fermilab and CERN-ISR energies. (26 refs)
QCD-motivated description of very high energy particle interactions
No full textCross sections for the production of secondaries with large transverse momentum can become comparable to the total cross section in the TeV energy range. It is argued that the onset of this effect is observed at sub TeV energies via an increase of the rapidity distribution near y = 0, an increase of p sub T with energy and, most directly, via a correlation between p sub T and multiplicity. If indeed scaling violations are associated with the hard scattering of partons, then scaling violations are largely confined to the central region and have little effect on cosmic ray data which are sensitive to the forward fragmentation region
Face Recognition for Cognitive Robots
No full textIn the near future the elderly population will increase in size up to a point that there are not enough people to provide support. One solution would be developing service robots, that can perform household tasks and in that way allow elderly to live longer independently. These service robots have to be able to adapt to changing environments, which requires a flexible framework that can recognize and learn objects regardless of the environment or the robot architecture. In this thesis such a framework, consisting of localization, description, classification and learning modules structured as a pipeline is introduced. Various types of objects require different methods to be used in each of the modules. For efficient memory usage these methods are dynamically loaded into the pipeline in the introduced framework. For human-robot interaction users have to be robustly identified and learned online. Exist-ing state of the art methods for face recognition, such as K-Nearest Neighbours (KNN) and Principal Component Analysis (PCA), do not support online learning of faces and lack the recognition performance required to be used in real-world situations. Hence the Class Average Principal Component Analysis (CAPCA) method is developed in this thesis as a descriptor. This method provides the required performance by increasing the separability of the classes by maximizing the inter-class and minimizing intra-class variations. The speed is increased significantly by selecting only the most representative samples. Additionally to allow for classification of unknown faces, the novel Certainty K-Nearest Neighbours (CertKNN) method has been introduced. The main benefit over the state of the art methods is finding the relation between the distance of classification and the certainty of that classification. This relation is automatically calculated from the data belonging to each class. In that way nearly optimal unknown classification can be done. Finally to further improve recognition performance a method has been developed that utilizes multiple frames in classification. To prove the benefits of the introduced methods extensive experiments have been performed on a state of the art face recognition database. The best performance was achieved with a F-measure of 96% and 90% for respectively known and unknown classification. Training speed was increased up to 100 times, which allows for online learning of faces. Lastly the introduced methods were applied on the Delft Robotics service robot and extensively tested in the RoboCup@Home challenge.BMDBioMechanical EngineeringMechanical, Maritime and Materials Engineerin
How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring
No full textWe observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10-29 e cm. © 2016 American Physical Society110141sciescopu
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Asymmetry analysis of target diagrams and mechanism for large transverse momenta. [10/sup 5/ GeV, parton model, quarks]
No full textA quantitative method is described for determining the amount of asymmetry present in target diagrams of secondaries from interactions of very high energy cosmic rays. Such asymmetries must appear if large transverse momenta reported in such experiments at approximately 10/sup 5/ GeV are due to hard scattering of constituents (partons, quarks) in the hadrons. This is currently the accepted explanation of high P/sub T/ phenomena at accelerator energies
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