Primary vertex finding is an important part of accurately reconstructing events at STAR since many physics parameters, such as transverse momentum for primary particles, depend on the vertex ...location. Many analyses depend on trigger selection and require an accurate determination of where the interaction that fired the trigger occurred. Here we present two vertex finding methods, the Pile-Up Proof Vertexer (PPV) and a Minuit based vertex finder (MinuitVF), and their performance on the 2008 STAR p+p and d+Au data. PPV had been developed for use in p+p collisions and uses a 1D truncated log-likelihood method to determine the most probable z location of the vertex. MinuitVF had been developed for Au+Au events and finds the vertex by determining the location where the distance of closet approach (DCA) for all tracks is at a minimum. The heart of MinuitVF is the Minuit routine, which is a standard tool that finds the minimum value of a multi-parameter function. We will present the vertex finding efficiency for both forward and mid-rapidity triggers. A comparison to a hardware determination of the vertex will also be included 1, 2.
The first measurement of the production of pions, kaons, (anti-)protons and ϕ mesons at midrapidity in Xe–Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV is presented. Transverse momentum ...(pT) spectra and pT-integrated yields are extracted in several centrality intervals bridging from p–Pb to mid-central Pb–Pb collisions in terms of final-state multiplicity. The study of Xe–Xe and Pb–Pb collisions allows systems at similar charged-particle multiplicities but with different initial geometrical eccentricities to be investigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow. In particular, this study shows that the radial flow does not depend on the colliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry, the previously observed smooth evolution of particle ratios with multiplicity from small to large collision systems is also found to hold in Xe–Xe. In addition, our results confirm that two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lower proton-to-pion ratio with respect to the thermal model expectations and the increase of the ϕ-to-pion ratio with increasing final-state multiplicity.
Autism is characterized by impairments in reciprocal communication and social interaction and by repetitive and stereotyped patterns of activities and interests. Evidence for a strong underlying ...genetic predisposition comes from twin and family studies, although susceptibility genes have not yet been identified. A whole-genome screen for linkage, using 83 sib pairs with autism, has been completed, and 119 markers have been genotyped in 13 candidate regions in a further 69 sib pairs. The addition of new families and markers provides further support for previous reports of linkages on chromosomes 7q and 16p. Two new regions of linkage have also been identified on chromosomes 2q and 17q. The most significant finding was a multipoint maximum LOD score (MLS) of 3.74 at marker D2S2188 on chromosome 2; this MLS increased to 4.80 when only sib pairs fulfilling strict diagnostic criteria were included. The susceptibility region on chromosome 7 was the next most significant, generating a multipoint MLS of 3.20 at marker D7S477. Chromosome 16 generated a multipoint MLS of 2.93 at D16S3102, whereas chromosome 17 generated a multipoint MLS of 2.34 at HTTINT2. With the addition of new families, there was no increased allele sharing at a number of other loci originally showing some evidence of linkage. These results support the continuing collection of multiplex sib-pair families to identify autism-susceptibility genes.
The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification ...and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/ in p–Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
With its large acceptance and particle identification coverage the NA49 experiment (Fig. 1) can study hadron production in a wide range of high energy reactions 1. Originally aimed at examining ...central Pb+Pb collisions for signatures of quark-gluon plasma formation, the scope of the experiment has been enhanced with a systematic study of impact parameter and projectile size dependence, as well as the inclusion of the more elementary p+p and p+A interactions. The question is: are predicted signals of the quark-gluon plasma observed and are there discontinuities which would support the concept of hadronic phase transition?
We know little about the psychological experiences of children and young people who have participated in virtual group music-making during the Coronavirus disease (COVID-19) pandemic. Adopting a ...mixed-methods design, we worked across three music education hubs in the UK, with a total 13 virtual music groups. These included a range of mainstream ensembles, inclusive ensembles targeting young people with special educational needs and/or disabilities, and inclusive music production spaces, targeting young people from lower socio-economic backgrounds. Reported progress in intra- and inter-personal psychological outcomes was investigated using quantitative and qualitative staff session reports, which were collected since before the pandemic (n1 for in-person sessions = 87, n2 for virtual sessions = 68), and surveys distributed to tutors, young people, and their parents during the first and second United Kingdom (UK) national lockdowns (n3 for qualitative responses = 240, n4 for quantitative responses = 96). Satisfaction of three basic psychological needs of self-determination theory and their relation to joint music-making in virtual spaces was also observed in real time by the researchers performing quantitative checklist observations on 16 separate occasions. Findings indicated that virtual music groups represented a meaningful psychological resource for the participating children and young people, especially considering the lack of opportunities offered by their schools and other extra-curricular activities. Through their participation with virtual group music-making activities, young people used music as a tool for self-expression and emotion management, restored lost musical identities and confidence, and preserved treasured social connections. Virtual alternatives to group music-making appear to indirectly nurture the sense of belongingness, mediated by supportive staff behaviors, but their direct connection, which has been widely reported for in-person group music-making experiences, has not been observed in virtual music groups.
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