In this paper we summarize the properties of v.sub.dyn and discuss briefly how the results can be interpreted in terms of a simple pair-production model. The ideas are then illustrated in detail with ...a PYTHIA simulation study of forward-backward correlations in pp collisions.
The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles ...in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90m3 and is operated in a 0.5T solenoidal magnetic field parallel to its axis.
In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb–Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.
The Internet has increasingly been studied as mode of delivery for interventions targeting problematic alcohol use. Most interventions have been fully automated, but some research suggests that ...adding counselor guidance may improve alcohol consumption outcomes.
An eight-module Internet-based self-help program based on cognitive behavioral therapy (CBT) was tested among Internet help-seekers. Eighty participants with problematic alcohol use according to the Alcohol Use Disorders Identification Test (AUDIT; scores of ≥ 6 for women and ≥ 8 for men) were recruited online from an open access website and randomized into three different groups. All groups were offered the same self-help program, but participants in two of the three groups received Internet-based counselor guidance in addition to the self-help program. One of the guidance groups was given a choice between guidance via asynchronous text messages or synchronous text-based chat, while the other guidance group received counselor guidance via asynchronous text messages only.
In the choice group, 65% (13 of 20 participants) chose guidance via asynchronous text messages. At the 10-week post-treatment follow-up, an intention-to-treat (ITT) analysis showed that participants in the two guidance groups (choice and messages) reported significantly lower past week alcohol consumption compared to the group without guidance; 10.8 (SD = 12.1) versus 22.6 (SD = 18.4); p = 0.001; Cohen's d = 0.77. Participants in both guidance groups reported significantly lower scores on the AUDIT at follow-up compared to the group without guidance, with a mean score of 14.4 (SD = 5.2) versus 18.2 (SD = 5.9); p = 0.003; Cohen's d = 0.68. A higher proportion of participants in the guidance groups said that they would recommend the program compared to the group without guidance (81% for choice; 93% for messages versus 47% for self-help).
Self-help programs for problematic alcohol use can be more effective in reducing alcohol consumption over a 10-week period when counselor guidance is added.
Clinicaltrials.gov NCT02384304.
The production of the hypertriton nuclei HΛ3 and HU+203EΛ-3 has been measured for the first time in Pb-Pb collisions at sNN=2.76 TeV with the ALICE experiment at LHC. The pT-integrated HΛ3 yield in ...one unity of rapidity, dN/dy×B.R.(HΛ3→He3,π-)=(3.86±0.77(stat.)±0.68(syst.))×10-in the 0-10% most central collisions, is consistent with the predictions from a statistical thermal model using the same temperature as for the light hadrons. The coalescence parameter B3 shows a dependence on the transverse momentum, similar to the B2 of deuterons and the B3 of 3He nuclei. The ratio of yields S3=HΛ3/(He3×Λ/p) was measured to be S3=0.60±0.13(stat.)±0.21(syst.) in 0-10% centrality events; this value is compared to different theoretical models. The measured S3 is compatible with thermal model predictions. The measured HΛ3 lifetime, τ=181-39+54(stat.)±33(syst.)ps is in agreement within 1σ with the world average value.
In this article we will discuss the previously proposed quantity {nu}{sub dyn}C. Pruneau, S. Gavin, and S. Voloshin, Phys. Rev. C 66, 044904 (2002), as a measure of the number-ratio fluctuations in ...high-energy particle production. We will show that {nu}{sub dyn} has pleasing mathematical properties making it ideal for the purpose. We will demonstrate its relation to two-particle correlations and how this measure can be generalized to higher-order correlations.
How to extract physics from νdyn Christiansen, P.; Haslum, E.; Stenlund, E.
Physics of atomic nuclei,
06/2012, Volume:
75, Issue:
6
Journal Article
Peer reviewed
In this paper we summarize the properties of
ν
dyn
and discuss briefly how the results can be interpreted in terms of a simple pair-production model. The ideas are then illustrated in detail with a ...PYTHIA simulation study of forward-backward correlations in
pp
collisions.
The influence of detector effects on TPC performance Christiansen, P.; Dobrin, A.; Gros, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2009, Volume:
609, Issue:
2
Journal Article
Peer reviewed
TPC stand alone simulations based on different energy loss models are compared to previously reported measurements with an ALICE TPC prototype. The performance obtained from simulations is shown to ...depend significantly on all the included detector effects stressing that energy loss model calculations alone are inadequate for describing the performance. When all effects are included, a good quantitative description of both the specific energy loss and the space point resolution can be obtained from all models. This shows that the TPC description in the official ALICE TPC simulation is in agreement with the measured test beam data.
Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions ...have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
PDF
