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Author |
Cauchi, M.; Assmann, R.W.; Bertarelli, A.; Carra, F.; Lari, L.; Rossi, A.; Mollicone, P.; Sammut, N. |
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Title |
Thermomechanical assessment of the effects of a jaw-beam angle during beam impact on Large Hadron Collider collimators |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review Special Topics-Accelerators and Beams |
Abbreviated Journal |
Phys. Rev. Spec. Top.-Accel. Beams |
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Volume |
18 |
Issue |
2 |
Pages |
021001 - 14pp |
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Keywords |
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Abstract |
The correct functioning of a collimation system is crucial to safely and successfully operate high-energy particle accelerators, such as the Large Hadron Collider (LHC). However, the requirements to handle high-intensity beams can be demanding, and accident scenarios must be well studied in order to assess if the collimator design is robust against possible error scenarios. One of the catastrophic, though not very probable, accident scenarios identified within the LHC is an asynchronous beam dump. In this case, one (or more) of the 15 precharged kicker circuits fires out of time with the abort gap, spraying beam pulses onto LHC machine elements before the machine protection system can fire the remaining kicker circuits and bring the beam to the dump. If a proton bunch directly hits a collimator during such an event, severe beam-induced damage such as magnet quenches and other equipment damage might result, with consequent downtime for the machine. This study investigates a number of newly defined jaw error cases, which include angular misalignment errors of the collimator jaw. A numerical finite element method approach is presented in order to precisely evaluate the thermomechanical response of tertiary collimators to beam impact. We identify the most critical and interesting cases, and show that a tilt of the jaw can actually mitigate the effect of an asynchronous dump on the collimators. Relevant collimator damage limits are taken into account, with the aim to identify optimal operational conditions for the LHC. |
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Address |
[Cauchi, Marija; Assmann, R. W.; Bertarelli, A.; Carra, F.; Lari, L.; Rossi, A.] CERN, Geneva, Switzerland, Email: marija.cauchi@cern.ch |
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Amer Physical Soc |
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English |
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Abbreviated Series Title |
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ISSN  |
1098-4402 |
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Expedition |
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Conference |
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Notes |
WOS:000352074600002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2178 |
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Author |
Cauchi, M.; Assmann, R.W.; Bertarelli, A.; Carra, F.; Cerutti, F.; Lari, L.; Redaelli, S.; Mollicone, P.; Sammut, N. |
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Title |
Thermomechanical response of Large Hadron Collider collimators to proton and ion beam impacts |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review Special Topics-Accelerators and Beams |
Abbreviated Journal |
Phys. Rev. Spec. Top.-Accel. Beams |
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Volume |
18 |
Issue |
4 |
Pages |
041002 - 14pp |
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Keywords |
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Abstract |
The CERN Large Hadron Collider (LHC) is designed to accelerate and bring into collision high-energy protons as well as heavy ions. Accidents involving direct beam impacts on collimators can happen in both cases. The LHC collimation system is designed to handle the demanding requirements of high-intensity proton beams. Although proton beams have 100 times higher beam power than the nominal LHC lead ion beams, specific problems might arise in case of ion losses due to different particle-collimator interaction mechanisms when compared to protons. This paper investigates and compares direct ion and proton beam impacts on collimators, in particular tertiary collimators (TCTs), made of the tungsten heavy alloy INERMET (R) 180. Recent measurements of the mechanical behavior of this alloy under static and dynamic loading conditions at different temperatures have been done and used for realistic estimates of the collimator response to beam impact. Using these new measurements, a numerical finite element method (FEM) approach is presented in this paper. Sequential fast-transient thermostructural analyses are performed in the elastic-plastic domain in order to evaluate and compare the thermomechanical response of TCTs in case of critical beam load cases involving proton and heavy ion beam impacts. |
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Address |
[Cauchi, Marija; Assmann, R. W.; Bertarelli, A.; Carra, F.; Cerutti, F.; Lari, L.; Redaelli, S.] CERN, CH-1211 Geneva 23, Switzerland, Email: marija.cauchi@cern.ch |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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ISSN |
1098-4402 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000352473800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2180 |
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Author |
Hinarejos, M.; Bañuls, M.C.; Perez, A. |
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Title |
Wigner formalism for a particle on an infinite lattice: dynamics and spin |
Type |
Journal Article |
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Year |
2015 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
17 |
Issue |
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Pages |
013037 - 16pp |
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Keywords |
Wigner functions; dynamics on a lattice; spin-dependent forces |
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Abstract |
The recently proposed Wigner function for a particle in an infinite lattice (Hinarejos M, Banuls MC and Perez A 2012 New J. Phys. 14 103009) is extended here to include an internal degree of freedom as spin. This extension is made by introducing a Wigner matrix. The formalism is developed to account for dynamical processes, with or without decoherence. We show explicit solutions for the case of Hamiltonian evolution under a position-dependent potential, and for evolution governed by a master equation under some simple models of decoherence, for which the Wigner matrix formalism is well suited. Discrete processes are also discussed. Finally, we discuss the possibility of introducing a negativity concept for the Wigner function in the case where the spin degree of freedom is included. |
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Address |
[Hinarejos, M.; Perez, A.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: banulsm@mpq.mpg.de |
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Publisher |
Iop Publishing Ltd |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
1367-2630 |
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Conference |
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Notes |
WOS:000348759800007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2101 |
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Author |
Liang, W.H.; Uchino, T.; Xiao, C.W.; Oset, E. |
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Title |
Baryon states with open charm in the extended local hidden gauge approach |
Type |
Journal Article |
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Year |
2015 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
51 |
Issue |
2 |
Pages |
16 - 14pp |
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Abstract |
In this paper we examine the interaction of DN and D* N states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the Weinberg-Tomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalar-baryon and vector-baryon states. We find two states with nearly zero width, which are associated to the I > (c) (2595) and I > (c) (2625). The lower state, with J (P) = 1/2(-), couples to DN and D* N, and the second one, with J (P) = 3/2(-), to D* N. In addition to these two I > (c) states, we find four more states with I = 0, one of them nearly degenerate in two states of J (P) = 1/2, 3/2. Furthermore we find three states in I = 1, two of them degenerate in J = 1/2, 3/2. |
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Address |
[Liang, W. H.] Guangxi Normal Univ, Dept Phys, Guilin 541004, Peoples R China, Email: liangwh@gxnu.edu.cn |
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Publisher |
Springer |
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 |
1434-6001 |
ISBN |
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Area |
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Conference |
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Notes |
WOS:000349297200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2105 |
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Author |
Bizzeti, P.G.; Sona, P.; Michelagnoli, C.; Melon, B.; Bazzacco, D.; Farnea, E.; Bizzeti-Sona, A.M.; de Angelis, G.; Gadea, A.; Gottardo, A.; Lunardi, S.; Menegazzo, R.; Mengoni, D.; Nannini, A.; Napoli, D.R.; Perego, A.; Recchia, F.; Sahin, E.; Valiente-Dobon, J.J.; Ur, C.A. |
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Title |
Analyzing power of AGATA triple clusters for gamma-ray linear polarization |
Type |
Journal Article |
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Year |
2015 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
51 |
Issue |
4 |
Pages |
49 - 11pp |
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Keywords |
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Abstract |
We have investigated the ability of AGATA triple clusters to measure the linear polarization of gamma rays, exploiting the azimuthal-angle dependence of the Compton scattering differential cross section. To this aim, partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of Pd-104 and Pd-108, which decay to the ground state by emission of gamma rays of 555.8 keV and 433.9 keV, respectively. Pulse-shape analysis and gamma-ray tracking techniques have been used to determine the position and time sequence of the interaction points inside the germanium crystals. Anisotropies in the detection efficiency have been taken into account using 661.6 keV gammas from a Cs-137 radioactive source. We obtain an average analyzing power of 0.451(34) at 433.9 keV and 0.484(24) at 555.8 keV. |
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Address |
[Bizzeti, P. G.; Sona, P.; Melon, B.; Bizzeti-Sona, A. M.; Perego, A.] Univ Florence, Dipartimento Fis, Florence, Italy, Email: bizzeti@fi.infn.it |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
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 |
1434-6001 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000353789600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2214 |
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| Permanent link to this record |
