| Records |
| Author |
Cabello, J.; Rafecas, M. |
| Title |
Comparison of basis functions for 3D PET reconstruction using a Monte Carlo system matrix |
Type |
Journal Article |
| Year |
2012 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
| Volume |
57 |
Issue |
7 |
Pages |
1759-1777 |
Keywords  |
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| Abstract |
In emission tomography, iterative statistical methods are accepted as the reconstruction algorithms that achieve the best image quality. The accuracy of these methods relies partly on the quality of the system response matrix (SRM) that characterizes the scanner. The more physical phenomena included in the SRM, the higher the SRM quality, and therefore higher image quality is obtained from the reconstruction process. High-resolution small animal scanners contain as many as 10(3)-10(4) small crystal pairs, while the field of view (FOV) is divided into hundreds of thousands of small voxels. These two characteristics have a significant impact on the number of elements to be calculated in the SRM. Monte Carlo (MC) methods have gained popularity as a way of calculating the SRM, due to the increased accuracy achievable, at the cost of introducing some statistical noise and long simulation times. In the work presented here the SRM is calculated using MC methods exploiting the cylindrical symmetries of the scanner, significantly reducing the simulation time necessary to calculate a high statistical quality SRM and the storage space necessary. The use of cylindrical symmetries makes polar voxels a convenient basis function. Alternatively, spherically symmetric basis functions result in improved noise properties compared to cubic and polar basis functions. The quality of reconstructed images using polar voxels, spherically symmetric basis functions on a polar grid, cubic voxels and post-reconstruction filtered polar and cubic voxels is compared from a noise and spatial resolution perspective. This study demonstrates that polar voxels perform as well as cubic voxels, reducing the simulation time necessary to calculate the SRM and the disk space necessary to store it. Results showed that spherically symmetric functions outperform polar and cubic basis functions in terms of noise properties, at the cost of slightly degraded spatial resolution, larger SRM file size and longer reconstruction times. However, we demonstrate that post-reconstruction smoothing, usually applied in emission imaging to reduce the level of noise, can produce a spatial resolution degradation of similar to 50%, while spherically symmetric basis functions produce a degradation of only similar to 6%, compared to polar and cubic voxels, at the same noise level. Therefore, the image quality trade-off obtained with blobs is higher than that obtained with cubic or polar voxels. |
| Address |
[Cabello, Jorge; Rafecas, Magdalena] Univ Valencia, Inst Fis Corpuscular, CSIC, Valencia, Spain, Email: jorge.cabello@ific.uv.es |
| Corporate Author |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0031-9155 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000302121000004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
955 |
| Permanent link to this record |
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| Author |
n_TOF Collaboration (Calviani, M. et al); Giubrone, G.; Tain, J.L. |
| Title |
Neutron-induced fission cross section of Cm-245: New results from data taken at the time-of-flight facility n_TOF |
Type |
Journal Article |
| Year |
2012 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
| Volume |
85 |
Issue |
3 |
Pages |
034616 - 10pp |
| Keywords |
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| Abstract |
The neutron-induced fission cross section of Cm-245 was measured at n_TOF in a wide energy range and with high resolution. The energy dependence, measured in a single measurement from 30 meV to 1 MeV neutron energy, has been determined with 5% accuracy relative to the U-235(n,f) cross section. In order to reduce the uncertainty on the absolute value, the data have been normalized at thermal energy to recent measurements performed at ILL and BR1. In the energy range of overlap, the results are in fair agreement with some previous measurements and confirm, on average, the evaluated cross section in the ENDF/B-VII.0 database, although sizable differences are observed for some important resonances below 20 eV. A similar behavior is observed relative to JENDL/AC-2008, a reactor-oriented database for actinides. The new results contribute to the overall improvement of the databases needed for the design of advanced reactor systems and may lead to refinements of fission models for the actinides. |
| Address |
[Calviani, M.; Gramegna, F.; Mastinu, P.; Sarchiapone, L.] Univ Padua, Ist Nazl Fis Nucl, Lab Nazl Legnaro, Padua, Italy, Email: marco.calviani@cern.ch |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0556-2813 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000302105100004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
956 |
| Permanent link to this record |
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| Author |
BABAR Collaboration (Lees, J.P. et al); Martinez-Vidal, F.; Oyanguren, A. |
| Title |
Amplitude analysis and measurement of the time-dependent CP asymmetry of B-0 -> (KSKSKS0)-K-0-K-0 decays |
Type |
Journal Article |
| Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
| Volume |
85 |
Issue |
5 |
Pages |
054023 - 21pp |
| Keywords |
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| Abstract |
We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B-0 -> (KSKSKS0)-K-0-K-0 obtained using 468 x 10(6) B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B-0 and (B) over bar (0) decays. We measure the total inclusive branching fraction B(B-0 -> (KSKSKS0)-K-0-K-0) = (6.19 +/- 0.48 +/- 0.15 +/- 0.12) x 10(-6), where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states f(0)(980), f(0)(1710), and f(2)(2010). Their respective product branching fractions are measured to be (2.70(-1.19)(+1.25) +/- 0.36 +/- 1.17) x 10(-6), (0.50(-0.24)(+0.46) +/- 0.04 +/- 0.10) x 10(-6), and (0.54(-0.20)(+0.21) +/- 0.03 +/- 0.52) x 10(-6). Additionally, we determine the mixing-induced CP-violation parameters to be S = -0.94(-0.21)(+0.24) +/- 0.06 and C = -0.17 +/- 0.18 +/- 0.04, where the first uncertainty is statistical and the second is systematic. These values are in agreement with the standard model expectation. For the first time, we report evidence of CP violation in B-0 -> (KSKSKS0)-K-0-K-0 decays; CP conservation is excluded at 3.8 standard deviations including systematic uncertainties. |
| Address |
[Lees, J. P.; Poireau, V.; Tisserand, V.] Univ Savoie, CNRS, IN2P3, Lab Annecy Le Vieux Phys Particules, F-74941 Annecy Le Vieux, France |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1550-7998 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000301973000004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
957 |
| Permanent link to this record |
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| Author |
Botella-Soler, V.; Glendinning, P. |
| Title |
Emergence of hierarchical networks and polysynchronous behaviour in simple adaptive systems |
Type |
Journal Article |
| Year |
2012 |
Publication |
Europhysics Letters |
Abbreviated Journal |
EPL |
| Volume |
97 |
Issue |
5 |
Pages |
50004 - 5pp |
| Keywords |
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| Abstract |
We describe the dynamics of a simple adaptive network. The network architecture evolves to a number of disconnected components on which the dynamics is characterized by the possibility of differently synchronized nodes within the same network (polysynchronous states). These systems may have implications for the evolutionary emergence of polysynchrony and hierarchical networks in physical or biological systems modeled by adaptive networks. |
| Address |
[Botella-Soler, V.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Valencia, Spain, Email: vicente.botella@uv.es |
| Corporate Author |
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Thesis |
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| Publisher |
Epl Association, European Physical Society |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0295-5075 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000301952600004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
958 |
| Permanent link to this record |
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| Author |
Montanari, D. et al; Gadea, A. |
| Title |
Gamma spectroscopy of calcium nuclei around doubly magic Ca-48 using heavy-ion transfer reactions |
Type |
Journal Article |
| Year |
2012 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
| Volume |
85 |
Issue |
4 |
Pages |
044301 - 21pp |
| Keywords |
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| Abstract |
The. decays of neutron-rich Ca isotopes around Ca-48 were measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using the heavy-ion transfer reactions Ca-48 on Ni-64 and Ca-48 on Pb-208 at approximate to 6 MeV/A. The work shows the feasibility to perform full in-beam gamma spectroscopy with heavy-ion transfer reactions (in terms of angular distributions, polarizations, and lifetimes analysis), providing a method that can be further exploited in the future with heavy targets and radioactive beams. For the one-neutron transfer channels, Ca-49 and Ca-47, shell-model and particle-vibration coupling calculations are used to understand the nature of the states. In particular, in both nuclei evidence is found for particle-vibration coupled states based on the 3(-) phonon of Ca-48. In the two-neutron transfer channels, Ca-46 and Ca-50, the experimental data are in global agreement with predictions based on full fp shell-model calculations. |
| Address |
[Montanari, D.; Leoni, S.; Bocchi, G.; Bortignon, P. F.; Bottoni, S.; Bracco, A.; Camera, F.; Casati, P.; Colo, G.; Corsi, A.; Crespi, F. C. L.; Nicolini, R.] Univ Milan, Dipartimento Fis, Milan, Italy, Email: silvia.leoni@mi.infn.it |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0556-2813 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000302237400002 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
963 |
| Permanent link to this record |
