15 research outputs found
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Antihypertensive efficacy and tolerability of candesartan-hydrochlorothiazide 32/12.5 mg and 32/25 mg in patients not optimally controlled with candesartan monotherapy
Aim. To evaluate the efficacy and tolerability of candesartan cilexetil 32 mg in combination with hydrochlorothiazide (HCT) 12.5 mg or 25 mg in hypertensive patients not optimally controlled with candesartan monotherapy. Patients and methods. A total of 3521 patients with treated or untreated hypertension and sitting diastolic blood pressure (DBP) 90-114 mmHg, entered a single-blind run-in phase with candesartan (16 mg for 2 weeks, followed by 32 mg for 6 weeks). At the end of the run-in phase, 1975 patients who still had DBP 90-114 mmHg were randomized to 8 weeks' double-blind treatment with either candesartan 32 mg (n=654), or candesartan-HCT 32/12.5 mg (n=656), or candesartan-HCT 32/25 mg (n=665). Principal results. At randomization, the mean blood pressure was similar in the three treatment groups (approximately 153/97 mmHg). It was reduced during the double-blind treatment phase by 6.1/5.6 mmHg in the candesartan 32 mg group, by 13.0/8.8 mmHg in the candesartan-HCT 32/12.5 mg group, and by 15.5/10.0 mmHg in the candesartan-HCT 32/25 mg group (p < 0.01 for all between treatment comparisons). All study treatments were generally well tolerated. Conclusion. Candesartan-HCT 32/12.5 mg and candesartan-HCT 32/25 mg are highly effective and provide improved blood pressure reduction and blood pressure control relative to candesartan 32 mg monotherapy, with maintained tolerability, in hypertensive patients whose blood pressure is not optimally controlled with candesartan monotherapy. Furthermore, candesartan-HCT 32/25 mg is more effective than candesartan-HCT 32/12.5 mg in this population
Measurement of the cross section for electromagnetic dissociation with neutron emission in Pb-Pb collisions at 1asNN=2.76 TeV
The first measurement of neutron emission in electromagnetic dissociation of Pb208 nuclei at the LHC is presented. The measurement is performed using the neutron zero degree calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at 1asNN=2.76 TeV with neutron emission are \u3c3singleEMD=187.4\ub10.2(stat) -11.2+13.2(syst) b and \u3c3mutualEMD=5.7\ub10.1(stat) \ub10.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model. \ua9 2012 CERN
Long-range angular correlationsof \u3c0, K and p in p\u2013Pb collisions at 1asNN =5.02TeV
Angular correlations between unidentified charged trigger particles and various species of charged associated particles (unidentified particles, pions, kaons, protons and antiprotons) are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV in the transverse-momentum range 0.3<pT<4 GeV/c. The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |\u3b7lab|<0.8. Fourier coefficients are extracted from the long-range correlations projected onto the azimuthal angle difference and studied as a function of pT and in intervals of event multiplicity. In high-multiplicity events, the second-order coefficient for protons, v2p, is observed to be smaller than that for pions, v2\u3c0, up to about pT=2 GeV/c. To reduce correlations due to jets, the per-trigger yield measured in low-multiplicity events is subtracted from that in high-multiplicity events. A two-ridge structure is obtained for all particle species. The Fourier decomposition of this structure shows that the second-order coefficients for pions and kaons are similar. The v2p is found to be smaller at low pT and larger at higher pT than v2\u3c0, with a crossing occurring at about 2 GeV/c. This is qualitatively similar to the elliptic-flow pattern observed in heavy-ion collisions. A mass ordering effect at low transverse momenta is consistent with expectations from hydrodynamic model calculations assuming a collectively expanding system
Femtoscopy of pp collisions at sqrt[s]=0.9 and 7\ua0TeV at the LHC with two-pion Bose-Einstein correlations
We report on the high statistics two-pion correlation functions from pp collisions at root s = 0.9 TeV and root s = 7 TeV, measured by the ALICE experiment at the Large Hadron Collider. The correlation functions as well as the extracted source radii scale with event multiplicity and pair momentum. When analyzed in the same multiplicity and pair transverse momentum range, the correlation is similar at the two collision energies. A three-dimensional femtoscopic analysis shows an increase of the emission zone with increasing event multiplicity as well as decreasing homogeneity lengths with increasing transverse momentum. The latter trend gets more pronounced as multiplicity increases. This suggests the development of space-momentum correlations, at least for collisions producing a high multiplicity of particles. We consider these trends in the context of previous femtoscopic studies in high-energy hadron and heavy-ion collisions and discuss possible underlying physics mechanisms. Detailed analysis of the correlation reveals an exponential shape in the outward and longitudinal directions, while the sideward remains a Gaussian. This is interpreted as a result of a significant contribution of strongly decaying resonances to the emission region shape. Significant nonfemtoscopic correlations are observed, and are argued to be the consequence of "mini-jet"-like structures extending to low p(t). They are well reproduced by the Monte-Carlo generators and seen also in pi(+)pi(-) correlations
Relationship between the mineralogical composition of the clay fraction of some andalusian caracteristic soils and theri behaviour in relation to potassium
12 páginas, 7 figuras, 3 tablas, 7 referencias.[ES]: Se estudia la fracción arcilla de los suelos más característicos de nuestra región
y su comportamiento frente al potasio, relacionándolo con la composición mineralógica
de dicha fracción.
Exceptuando el suelo fersialítico, los diferentes horizontes de cada suelo no presentan
variaciones importantes en su comportamiento frente al potasio.
Los suelos vérticos litomorfos y vérticos topomorfos presentan los valores más
altos de Kx, lo que está de acuerdo con una mayor edafización y con altas concentraciones
de montmorillonita e ilita. El suelo calcimorfo, a pesar de poseer composición
mineralógica simlar, está muy poco evolucionado y presenta valores más
bajos de Kx, similares a los del suelo aluvial, que está asimismo poco evolucionado,
con alta proporción de ilita, a la que acompañan pequeñas proporciones de montmorillonita
y caolinita. En el suelo fersialítico lavado disminuye el valor de Kx, al
descender en el perfil, en el mismo sentido en que disminuye la ilita y aumenta la
montmorillonita. Los horizontes C de los suelos de gran desarrollo edafogenético
presentan en relación con los horizontes superiores, a pesar de poseer composición
mineralógica similar, valores muy pequeños de Kx. El grado de desarrollo del suelo
es el que tiene mayor influencia en los valores de Kx.
Los tratamientos de eliminación de materia orgánica y/o geles producen un aumento
muy apreciable de los valores de Kx.[EN]: The clay fractions of soils caracteristic of western Anclalucía and their behaviour
in relation to potassium are studied, and the latter in related to the mineralogical
composition of the former.
Except the "fersialitico soil" (Rhocloxeralfs), the various horizons of each soil
do not present distinct variations in their behaviour in relation to potassium.
The "vertisol litomorfo" (chromoxererts) and «topomorfo» (Pelloxererts) soils
present the highest values of Kx which agrees with the strong weathering of these
soils and their nigh proportions of montmoillonite and illite. The "calcimorfo soil" (Calciorthids) is little weathered and present lower values of Kx, despite its mineralogical
composition, which is analogous to the preceding soils. Similarly low values
of Kx are obtained for the «aluvial soil» (Xerofluvents), also little weathered, which
contains high proportion of illite, with small amounts of montmorillonite and kaolinite.
The value of Kx and the proportion of illite for the leached fersialitico soil
decrease and the proportion of montmorillonite increases as getting down across the
profile.
C horizons of soils with high podogenic development present much lower values
of Kx than upper horizona, despite the analogy of their mineralogical compositions.
The degree of development of soils has the highest influence on Kx, values.
Treatments for removing organic matter and/or gels originate important increases
in Kx values.Peer reviewe
Centrality dependence of \u3c0, K, and p production in Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV
In this paper measurements are presented of \u3c0\ub1, K\ub1, p, and p(bar) production at midrapidity (|y| < 0.5), in Pb-Pb collisions at 1asNN= 2.76 TeV as a function of centrality. The measurement covers the transverse-momentum (pT ) range from 100, 200, and 300 MeV/c up to 3, 3, and 4.6 GeV/c for \u3c0, K, and p, respectively. The measured pT distributions and yields are compared to expectations based on hydrodynamic, thermal and recombination models. The spectral shapes of central collisions show a stronger radial flow than measured at lower energies, which can be described in hydrodynamic models. In peripheral collisions, the pT distributions are not well reproduced by hydrodynamic models. Ratios of integrated particle yields are found to be nearly independent of centrality. The yield of protons normalized to pions is a factor 3c1.5 lower than the expectation from thermal models
J/\u3c8 Elliptic Flow in Pb-Pb Collisions at sqrt[s_{NN}]=2.76\u2009\u2009TeV
We report on the first measurement of inclusive J/\u3c8 elliptic flow v2 in heavy-ion collisions at the LHC. The measurement is performed with the ALICE detector in Pb-Pb collisions at 1asNN=2.76 TeV in the rapidity range 2,5<y<4,0. The dependence of the J=c v2 on the collision centrality and on the J/\u3c8 transverse momentum is studied in the range 0 64pT 64 10 GeV/c. For semicentral Pb-Pb collisions at 1asNN=2.76 TeV, an indication of nonzero v2 is observed with a largest measured value of v2=0.116 \ub1 0.046 (stat) \ub1 0:029 (syst) for J/\u3c8 in the transverse momentum range 2 64 pT 64 4 GeV/c. The elliptic flow measurement complements the previously reported ALICE results on the inclusive J/\u3c8 nuclear modification factor and favors the scenario of a significant fraction of J/\u3c8 production from charm quarks in a deconfined partonic phase