| 1. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 2. |
- Bengtsson, Lars, et al.
(författare)
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Field investigation of winter thermo‐ and hydrodynamics in a small Karelian lake
- 1996
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 41:7, s. 1502-1502
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Tidskriftsartikel (refereegranskat)abstract
- During late winter (18 March–7 April 1994), temperature and current measurements were made in Lake Vendyurskoe, Russia, including three surveys at six cross sections of the lake. Also, the temperature profile evolution was registered with two thermistor chains at two stations (bottom depths of 7.6 and 11.5 m) until the time of ice breakup. Temperature gradients were measured just below the ice cover and in the upper 10‐cm layer of the bottom sediments.The isotherms were found to be almost horizontal and evenly spaced vertically, so no conditions for large‐scale, density‐induced currents existed. The heat flux from sediments to water ranged from 0.6 to 2.0 W m−2. These values were inversely related to the depth. The heat flux from water to ice ranged from 0.7 to 1.2 W m−2. When water heating from solar radiation penetration became apparent, this flux increased by a factor of two. When solar radiation increased, convection occurred in the upper layers of the water column. When solar radiation heating became significant at the beginning of spring, the average net heat flux at the ice‐water interface during daytime was 7.7 W m−2. Weak currents (few mm s−1) with a seiche‐like character were observed, which most likely resulted from ice‐cover oscillations.
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| 3. |
- Malm, Joakim, et al.
(författare)
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Field study on currents in a shallow, ice‐covered lake
- 1998
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 43:7, s. 1669-1679
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Tidskriftsartikel (refereegranskat)abstract
- A field study on current structure and circulation characteristics in Lake Vendyurskoe, a small, shallow, icecovered lake in Karelia, Russia, is presented. The current velocity magnitudes were generally found to be small. The most pronounced currents had an oscillating character, with velocity amplitudes on the order of millimeters per second. The oscillation period, obtained from spectral density calculations, corresponded to that of a barotropic uninodal seiche. The seichelike nature of the current oscillations was supported by the results from analysis of icelevel fluctuations, giving identical periods and a phase shift of one‐fourth the period between the two types of oscillations. Mean currents measured during the winter were on the order of millimeters per second. Because Lake Vendyurskoe does not have any significant river inflow or outflow during winter, the most probable cause of these currents is horizontal temperature (pressure) gradients. Scaling analysis indicated that these currents are geostrophic. This was supported by theoretical estimates, based on observed horizontal temperature gradients, being of the same order as the observed currents. The mean current velocities increased considerably after spring convection from <1 to several millimeters per second.
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