Rodriguez-Alvarez, M. J., Sanchez, F., Soriano, A., Iborra, A., & Mora, C. (2011). Exploiting symmetries for weight matrix design in CT imaging. Math. Comput. Model., 54(7-8), 1655–1664.
Abstract: In this paper we propose several methods of constructing the system matrix (SM) of a Computed Tomography (CT) scanner with two objectives: (1) to construct SMs in the shortest possible time and store them in an ordinary PC without losing quality, (2) to analyze the possible applications of the proposed method to 3D, taking into account SMs' sizes, computing time and reconstructed image quality. In order to build the SM, we propose two new field of view (FOV) pixellation schemes, based on a polar coordinate system (polar grid) by taking advantage of the polar rotation symmetries of CT devices. Comparisons between the SMs proposed are performed using two phantom and a real CT-simulator images. Global error, contrast, noise and homogeneity of the reconstructed images are discussed.
|
SciBooNE Collaboration(Cheng, G. et al), Catala-Perez, J., Gomez-Cadenas, J. J., & Sorel, M. (2011). Measurement of K(+) production cross section by 8 GeV protons using high-energy neutrino interactions in the SciBooNE detector. Phys. Rev. D, 84(1), 012009–22pp.
Abstract: The SciBooNE Collaboration reports K(+) production cross section and rate measurements using high-energy daughter muon neutrino scattering data off the SciBar polystyrene (C(8)H(8)) target in the SciBooNE detector. The K(+) mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure d(2)sigma/dpd Omega = (5.34 +/- 0.76) mb/(GeV/c x sr) for p + Be -> K(+) + X at mean K(+) energy of 3.9 GeVand angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K(+) sample. Compared to Monte Carlo predictions using previous higher energy K(+) production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85 +/- 0.12. This agreement is evidence that the extrapolation of the higher energy K(+) measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K(+) production cross section from 40% to 14%.
|
Xie, J. J., Chen, H. X., & Oset, E. (2011). The pp -> p Lambda K(+) and pp -> p Sigma(0)K(+) reactions with chiral dynamics. Phys. Rev. C, 84(3), 034004–8pp.
Abstract: We report on a theoretical study of the pp -> p Lambda K(+) and pp -> p Sigma(0)K(+) reactions near threshold using a chiral dynamical approach. The production process is described by single-pion and single-kaon exchange. The final state interactions of nucleon-hyperon, K-hyperon, and K-nucleon systems are also taken into account. We show that our model leads to a fair description of the experimental data on the total cross section of the pp -> p Lambda K(+) and pp -> p Sigma(0)K(+) reactions. We find that the experimental observed strong suppression of Sigma(0) production compared to Lambda production at the same excess energy can be explained. However, ignorance of phases between some amplitudes does not allow one to properly account for the nucleon-hyperon final state interaction for the pp -> p Sigma(0)K(+) reaction. We also demonstrate that the invariant mass distribution and the Dalitz plot provide direct information about the Lambda and Sigma(0) production mechanisms and may be tested by experiments at COSY or HIRFL-CSR.
|
Mendez, V., Amoros, G., & Kaci, M. (2011). A Decentralized Deployment Strategy and Performance Evaluation of LCG File Catalog Service. J. Grid Comput., 9(3), 345–354.
Abstract: The LHC Computing Grid (LCG) leads by CERN, has solved with the LCG File Catalog (LFC) the major problem of scaling the data management catalog. However, additional performance issues should be faced to deploy a painless catalog service. With this aim, we present a decentralized LFC server configuration, and its performance evaluation compared with the traditional LFC deployment. A performance analysis is shown, including not only the catalog server, but also analysing the client side overhead. We find that the LFC service has in the clients a relevant workload of the overall service. The experimental results show that the proposed LFC deployment for servers and clients, improves the performance of the service.
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Measurement of the inelastic proton-proton cross-section at sqrt(s)=7 TeV with the ATLAS detector. Nat. Commun., 2, 463–14pp.
Abstract: The dependence of the rate of proton-proton interactions on the centre-of-mass collision energy, root s, is of fundamental importance for both hadron collider physics and particle astrophysics. The dependence cannot yet be calculated from first principles; therefore, experimental measurements are needed. Here we present the first measurement of the inelastic proton-proton interaction cross-section at a centre-of-mass energy, root s, of 7 TeV using the ATLAS detector at the Large Hadron Collider. Events are selected by requiring hits on scintillation counters mounted in the forward region of the detector. An inelastic crosssection of 60.3 +/- 2.1 mb is measured for xi > 5x10(-6), where xi is calculated from the invariant mass, M(X), of hadrons selected using the largest rapidity gap in the event. For diffractive events, this corresponds to requiring at least one of the dissociation masses to be larger than 15.7 GeV.
|
Algora, A. et al, Jordan, D., Tain, J. L., Rubio, B., Agramunt, J., Perez-Cerdan, A. B., et al. (2011). Improvements on Decay Heat Summation Calculations by Means of Total Absorption Gamma-ray Spectroscopy Measurements. J. Korean Phys. Soc., 59(2), 1479–1482.
Abstract: The decay heat of fission products plays an important role in predictions of the heat released by nuclear fuel in reactors. In this contribution we present results of the analysis of the measurement of the beta decay of some refractory isotopes that were considered possible important contributors to the decay heat in reactors. The measurements presented here were performed at the IGISOL facility of the University of Jyvaskyla, Finland. In our measurements we have combined for the first time a Penning trap (JYFLTRAP), which was used as a high resolution isobaric separator, with a total absorption spectrometer. The results of the measurements as well as their consequences for decay heat summation calculations are discussed.
|
Tain, J. L. et al, Algora, A., Estevez, E., Rubio, B., Valencia, E., & Jordan, D. (2011). Beta Decay Studies of Neutron Rich Nuclei Using Total Absorption Gamma-ray Spectroscopy and Delayed Neutron Measurements. J. Korean Phys. Soc., 59(2), 1499–1502.
Abstract: A complete characterisation of the beta-decay of neutron-rich nuclei can be obtained from the measurement of beta-delayed gamma rays and, whenever the process is energetically possible, beta-delayed neutrons. The accurate determination of the beta-intensity distribution and the beta-delayed neutron emission probability is of great relevance in the fields of reactor technology and nuclear astrophysics. A programme for combined measurements using the total absorption gamma-ray spectroscopy technique and both neutron counters and neutron time-of-flight spectrometers is presented.
|
n_TOF Collaboration(Guerrero, C. et al), Domingo-Pardo, C., & Tain, J. L. (2011). Study of Photon Strength Function of Actinides: the Case of (235)U, (238)Np and (241)Pu. J. Korean Phys. Soc., 59(2), 1510–1513.
Abstract: The decay from excited levels in medium and heavy nuclei can be described in a statistical approach by means of Photon Strength Functions and Level Density distributions. The study of electromagnetic cascades following neutron capture based on the use of high efficiency detectors has been shown to be well suited for probing the properties of the Photon Strength Function of heavy (high level density) and/or radioactive (high background) nuclei. In this work we have investigated for the first time the validity of the recommended PSF of actinides, in particular (235)U, (238)Np and (241)Pu. Our study includes the search for resonance structures in the PSF below S(n) and draws conclusions regarding their existence and their characteristics in terms of energy, width and electromagnetic nature.
|
Pino, F., Roe, N., Orero, A., Falcon, C., Rojas, S., Benlloch, J. M., et al. (2011). Development of a variable-radius pinhole SPECT system with a portable gamma camera. Rev. Esp. Med. Nucl., 30(5), 286–291.
Abstract: Objective: To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube. Material and methods: The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out. Results: Resolution values, ranging from 1.0 mm for a radius of 21.4 mm and 1.4 mm for a radius of 37.2 mm were obtained, thereby justifying the interest of a variable radius SPECT system. Conclusions: The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging.
|
Yoshida, T., Hagura, N., Umezu, R., Algora, A., Tain, J. L., Jordan, D., et al. (2011). Impact of TAGS Measurement on FP Decay Data and Decay Heat Calculations. J. Korean Phys. Soc., 59(2), 1543–1546.
Abstract: Nuclear level schemes are usually constructed from the high-resolution data of the gamma-ray transitions which immediately follow the beta-decay of their parents. It is recognized that this procedure may lead to the “pandemonium problem”. If we use the decay data suffering from the pandemonium problem for the decay heat calculations the beta-ray component will be overestimated and the gamma-ray component underestimated. The beta-feeding data obtained by the total absorption gamma-ray spectroscopy (TAGS) is proved to be free from this problem. In the case of the Japanese data base for the FP decay heat calculation, the theoretical values based on the gross theory of beta-decay are widely introduced to circumvent the pandemonium problem. The gross theory, however, is not good at describing any beta-transition exclusively concentrating to a single level in the daughter nucleus. The TAGS method is also proved to be able to save this situation. Further, we have to change our comprehension over the currently published decay schemes.
|
