| 1. |
- Abelev, Betty, et al.
(author)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Journal article (peer-reviewed)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(author)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(author)
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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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In: Journal of High Energy Physics. - 1029-8479. ; :7
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Journal article (peer-reviewed)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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| 8. |
- Bignert, Anders, et al.
(author)
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Comments Concerning the National Swedish Contaminant Monitoring Programme in Marine Biota, 2015
- 2015
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Reports (other academic/artistic)abstract
- The environmental toxicants examined in this report can be classified into five groups – heavy metals, chlorinated compounds, brominated flame retardants, polyaromatic hydrocarbons and perfluorinated compounds. Each of these contaminants have been examined from various sites for up to six different fish species, in blue mussels, and in guillemot eggs, for varying lengths of time. The following summary examines overall trends, spatial and temporal, for the five groups.Condition and Fat ContentCondition and fat content in different species tended to follow the same pattern at the same sites, with a few exceptions. Most of the fish species generally displayed a decreasing trend in both condition and fat content at most sites examined. Exceptions to this were increases in condition factor seen in cod liver at Fladen, perch muscle at Kvädöfjärden, and for herring at Ängskärsklubb in spring. Also, an increase in fat content was seen during the most recent ten years for herring at Ängskärsklubb in spring. There were also some sites where no log linear trends were seen.Heavy MetalsDue to a change in methods for metal analysis (not mercury) in 2004, values between 2003 and 2007 should be interpreted with care. From 2009 metals are analyzed at ACES, Stockholm University.Generally, higher mercury concentrations are found in the Bothnian Bay, but also from one station in the Northern parts of Baltic Proper, compared to other parts of the Swedish coastline. The time series show varying concentrations over the study period. The longer time series in guillemot egg and spring-caught herring from the southern Bothnian Sea and southern Baltic Proper show significant decreases of mercury. On the other hand, increasing concentrations are seen in e.g., cod muscle, but the concentrations are fairly low compared to measured concentrations in perch from fresh water and coastal sites. In most cases, the mercury concentrations are above the EQSbiota of 20 ng/g wet weight.Lead is generally decreasing over the study period (in time series of sufficient length), supposedly due to the elimination of lead in gasoline. The highest concentrations are seen in the southern part of the Baltic Sea. Elevated lead concentrations between 2003 and 2007 (e.g. Harufjärden) should be viewed with caution (see above regarding change in analysis methods). Lead concentrations are below the suggested target level at all stations.Cadmium concentrations show varying non-linear trends over the monitored period. It is worth noting that despite several measures taken to reduce discharges of cadmium, generally the most recent concentrations are similar to concentrations measured 30 yearsago in the longer time series. Cadmium concentrations in herring and perch are all below the suggested target level of 160 μg/kg wet weight.The reported nickel concentrations show no consistent decreasing trends. Some series begin with two elevated values that exert a strong leverage effect on the regression line and may give a false impression of decreasing trends. Chromium generally shows decreasing concentrations, possibly explained by a shift in analytical method. The essential trace metals, copper and zinc, show no consistent trends during the monitored period.Generally higher concentrations of arsenic and silver are found along the west coast compared to other parts of the Sweadish coast line. However for silver a few stations in the Bothnian Sea and Bothnian Bay show comparable concentrations to the west coast stations.Chlorinated CompoundsGenerally, a decreasing concentrations were observed for all compounds (DDT’s, PCB’s, HCH’s, HCB) in all species examined, with a few exceptions, such as no change in TCDD-equivalents being seen in herring muscle (except at Änskärsklubb where very high concentrations at the beginning of the sampling period were seen and also at the west coast station Fladen). The longer time-series in guillemot also show a marked decrease in TCDD-equivalents from the start in the late 1960s until about 1985 from where no change occurred for many years, however, during the most recent ten years a decrease in the concentration is seen. Concentrations of DDE and CB-118 are for some species and sites still above their respective target levels.The chlorinated compounds generally show higher concentrations in the Bothnian Sea and/or Baltic Proper when compared to the Bothnian Bay and the Swedish west coast.Brominated Flame RetardantsElevated levels of HBCDD are seen in sites from the Baltic Proper, while the investigated PBDEs show higher concentrations in the Bothnian Bay. In addition, lower concentrations of all investigated PBDEs and HBCDD are seen on the Swedish west coast compared to the east coast. Temporally, significant increases in BDE-47, -99 and -100 have been seen in guillemot eggs since the late 1960s until the early 1990s, where concentrations then began to show decreases. Also, the concentration of HBCDD in guillemot eggs shows a decrease during the most recent ten years. For fish and blue mussels, BDE-47, -99, and -153 decreased at some sites and showed no trend at other sites. The concentration of HBCDD in fish and blue mussels showed inconsistent trends. The concentration of HBCDD is below the EQSbiota of 167 μg/kg wet weight for all fish species from all areas, while the concentration of BDE-47 alone is above the EQSbiota for sumPBDE of 0.0085 ng/g wet weight.PAHsOnly blue mussels have been examined for spatial differences in PAH concentrations. Concentration of ΣPAH was found to be higher from Kvädöfjärden in the Baltic Proper compared to stations at the West coast, but individual PAHs showed varying spatial patterns. Over time, acenaphthalene was rarely found above the detection limit. Significant decreasing trends were observed for ΣPAH, chrysene, fluoranthene and pyrene at Fjällbacka; for naphthalene at Kvädöfjärden; and for pyrene at Fladen.All time series where concentrations of various PAHs were compared with the target value based on OSPAR Ecological Assessment Criteria, or EC Environmental Quality Standards were below the target value.PFASsPFHxS and PFOS show a similar spatial pattern, but PFOS concentrations were approximately 25 times higher than PFHxS levels. The distribution of PFOS is quite homogenous along the Swedish coast but with somewhat higher concentrations in the Baltic Proper. PFOS concentrations in guillemot eggs are about 100-200 times higher than in herring liver. An overall increasing concentration of PFOS in guillemot eggs has been observed throughout the whole time period, however, during the most recent ten years, a change of direction is detected. The longer herring time series from Harufjärden, Landsort, and Utlängan show increasing concentrations for PFOS and most carboxylates. For FOSA, on the other hand, decreasing concentrations are seen during the most recent ten years.Organotin compoundsThe majority of the analysed tinorganic compounds showed concentrations below LOQ. However TBT and DPhT showed concentrations above LOQ at all stations with highest reported concentrations in fish from Örefjärden in the northern part of Bothnian Sea.
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| 9. |
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| 10. |
- Danielsson, Sara, et al.
(author)
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Contaminants in fish from potentially polluted sites along the Swedish coast with the nationalmonitoring programme as reference
- 2014
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Reports (other academic/artistic)abstract
- In this report, fish from potentially polluted sites along the coast of Sweden were analysed for several contaminants and when possible also compared with concentrations in fish fromreference sites used within the national monitoring programme for contaminants in marinebiota. However, it is important to have in mind that for the polluted sites, sampling has onlybeen carried one single year and only two pooled samples were analysed from each site,which could have effects on the representativeness and the uncertainty of the results.Generally, perch and herring from Lilla Värtan had the highest concentrations of mercury,lead, nickel, silver, CB-153 and CB-118, DDE, dioxins, brominated flame retardants,perfluorinated chemicals, chlorinated paraffins and organotin compounds compared to theother polluted sites. Among the stations where eelpout and cod were sampled, Rivöfjord hadhighest concentration of several contaminants. The contaminants include mercury, lead,chromium, CB-153 and CB-118, dioxins, brominated flame retardants, perfluorinatedchemicals, chlorinated paraffins and organotin compounds. It is not very surprising that these two areas show the highest concentrations of several of the investigated contaminants in fish.Lilla Värtan is situated in Stockholm and hence is affected by the big city, in addition, heavyboat traffic of different kinds are taking place in this water along with several other harmfulenvironmental activities in this area. SCCP showed the highest concentrations in herring fromLilla Värtan, while perch on the contrary had the lowest concentration of SCCP among all ofthe perch sites. This is however difficult to explain. Rivö fjord is situated just outsideGothenburg city and is thus affected by activities in the city. Also, the main part ofGothenburg’s harbor activities takes place close by Rivö fjord. Moreover, Ryaverken, whichis a sewage treatment plant, and two refineries are also affecting the water. Thus, the twolargest cities in Sweden contribute with a cocktail of contaminants to its surrounding waters.In addition, fish from Skelleftebukten, herring and/or perch, had elevated concentrations oflead, cadmium, nickel, copper, HCB and BDE-47 and -154. The elevated concentrations ofdifferent metals in this area could be caused by Rönnskärsverken, which releases metals. Inaddition, there are several industries and mining practices in the area that could havecontributed with high metal levels. Furthermore, dismantlement activities might contributewith the high levels of brominated flame retardants found in this area.Kungsbackafjorden, on the Swedish west coast, had high concentrations of cadmium andcopper in cod and high concentrations of perfluorinated chemicals in both eelpout and cod.There is a sewage treatment plant in the area, which might be one explanation for elevatedconcentrations of perfluorinated chemicals.Most of the other selected polluted sites for this study had none or just a few contaminantsthat differed from the reference sites in the vicinity. Thus it seems that these sites might not be as burdened by local sources of the investigated substances as has been assumed. On the other hand, when comparing the concentrations with their target values, a few of the contaminants at these sites were above the target values, this included mercury, CB-118, PBDEs and TBT.However, the concentrations were not significantly different from reference values, whichindicates a more widespread problem concerning these contaminants.When comparing contaminant concentrations with their respective target value, mercuryconcentrations exceeded the target value for all species at all sites except for herring fromÖrnsköldsviksfjärden. Lead was below the target value at all sites and cadmium was alsobelow at all sites except for perch from Skelleftebukten, which exceeded the target value.4 CB-153 was in general below the target value, but cod from Rivö fjord and perch from LillaVärtan exceeded it. In contrast, most polluted sites were above the target value for CB-118with a few exceptions. Concentrations of DDE were generally below the target value,however perch and herring from Lilla Värtan exceeded it and concentrations of DDE in codliver were also above, while the concentration in cod muscle were below target value. HCHs,HCB, dioxins, PFOS and HBCDD were below target values for all species at all sites. PBDEson the other hand exceed the target value for all species at all sites. Concentrations of thepriority substances, DEHP (Di-(2-ethylhexyl)-phthalate), HCBD (Hexachlorobutadiene), andPeCB (Pentachlorobenzene) were below the target values, these compounds were even below LOQ at most sites. SCCP (short-chained chlorinated paraffins) were well below the target level for all species at all sites. TBT on the other hand, were in perch above the target value at all sites except at Inre Slätbaken and Skelleftebukten. Yttre fjärden and Lilla Värtan had the highest concentrations of TBT and here the target value was also exceeded in herring. Eelpout and cod had concentrations of TBT below the target value.In conclusion, Lilla Värtan seems to be the site with the highest concentrations of severalcontaminants and also where several of these exceed the target values. Rivö fjord andSkelleftebukten also had higher concentrations of several contaminants compared to the other polluted sites.
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