Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions at √sNN=2.76 TeV

Abstract: The anisotropy of the azimuthal distributions of charged particles produced in √s_(NN)=2.76 TeV PbPb collisions is studied with the CMS experiment at the LHC. The elliptic anisotropy parameter, v_2, defined as the second coefficient in a Fourier expansion of the particle invariant yields, is extracted using the event-plane method, two- and four-particle cumulants, and Lee-Yang zeros. The anisotropy is presented as a function of transverse momentum (p_T), pseudorapidity (η) over a broad kinematic range, 0.3

Complementary PET studies of striatal neuronal function in the differential diagnosis between multiple system atrophy and Parkinson's disease

Abstract: We used PET with the tracers [18F]fluorodeoxyglucose (FDG), [18F]fluorodopa (FDOPA) and [11C]raclopride (RACLO) to study striatal glucose and dopa metabolism, and dopamine D2 receptor binding, respectively, in nine patients with multiple system atrophy. Ten patients with classical Parkinson's disease were investigated with the same three PET tracers' and three separate groups, each of 10 healthy subjects, served as control populations. We found that striatal FDOPA values separated all healthy subjects from patients with parkinsonism but they were not useful in distinguishing multiple system atrophy from Parkinson's disease. Conversely, striatal RACLO as well as FDG values discriminated all multiple system atrophy from Parkinson's disease patients as well as from healthy control subjects. Metabolic and receptor binding decrements in the putamen of multiple system atrophy patients were significantly correlated. Stepwise regression analysis revealed that a linear combination of putamen RACLO and FDOPA values accurately predicted clinical measures of disease severity in the multiple system atrophy group. Our findings suggest that striatal FDG and particularly RACLO are sensitive and effective measures of striatal function and may help characterizing patients with multiple system atrophy. In contrast, FDOPA measurements are accurate in detecting abnormalities of the nigrostriatal dopaminergic system but may not distinguish among different forms of parkinsonism.

Cosmogenic nuclide evidence for low weathering and denudation in the wet, tropical highlands of Sri Lanka

Abstract: [1] Some of the lowest weathering and erosion rates in any mountain range in the world have been measured using cosmogenic nuclides in the steep, humid, tropical highlands of Sri Lanka. The total preanthropogenic denudation rates were measured in creek sediments and soil samples from unperturbed rain forest sites, bedrock from mountain crests, and bedrock from inselbergs. Denudation rates are in the range of 5–30 t km−2 yr−1 (2–11 mm ky−1). These rates average denudation over the last 50–250 ky. Weathering exports in rivers draining the mountainous Central Highlands show that silicate weathering rates are also low, varying from 5 to 20 t km−2 yr−1 today (2–7 mm ky−1), but they represent a significant fraction of the total denudation. All these observations run contrary to the conventional geomorphologic and geochemical wisdom that would predict rapid erosion for highlands of high relief, temperatures, and precipitation. We speculate that the high relief in Sri Lanka represents the remnant of a geomorphic block that was uplifted during rifting at 130 Ma or even earlier and that was reduced to the interior of the island by rapid receding of escarpments after continental breakup. It is possible that throughout this history, hillslopes, where not exposing bare bedrock, were protected by thick weathered profiles. Such clay-rich layers would inhibit silicate weathering by shielding bedrock from weathering agents. In the absence of landscape rejuvenation, physical erosion rates are low, and fresh mineral surfaces are not being supplied. The observation that wet, steep, tropical highlands can have low rates of rock weathering and erosion has some potentially profound implications for the long-term controls of atmospheric CO2 budgets: High temperature and precipitation, which are much invoked though controversial agents for silicate dissolution and CO2 drawdown, become ineffective in promoting weathering in areas that are not tectonically active.

Search for Heavy Neutral Leptons in Events with Three Charged Leptons in Proton-Proton Collisions at √s = 13 TeV

Abstract: A search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination of electrons and muons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 35.9 fb^(−1). The search is performed in the N mass range between 1 GeV and 1.2 TeV. The data are found to be consistent with the expected standard model background. Upper limits are set on the values of |V_(eN)|^2and |V_(μN)|^2, where V_(lN) is the matrix element describing the mixing of N with the standard model neutrino of flavor l. These are the first direct limits for N masses above 500 GeV and the first limits obtained at a hadron collider for N masses below 40 GeV.