110626236
Tests of MVD prototype pad detector with a β- source
Abstract The MVD group has been testing two versions of silicon pad detectors. One design uses a single metal layer for readout trace routing. The second type uses two layers of metal, allowing for greatly simplified signal routing. However, because the readout traces for the pads pass over the other pads in the same column (separated by an oxide layer), the double-metal design introduces crosstalk into the system. A simple test stand using a 90 Sr β − source with scintillator triggers was made to estimate the crosstalk. The crosstalk between pads in the same column of the pad detector was 1.6–3.1%. The values measured between pads in different columns were very close to zero. The measured crosstalk was below our maximum allowed value of 7.8%.
121797308
Simultaneous multiplicity and forward energy characterization of particle spectra in Au + Au collisions at 11.6-A-GeV/c
In this paper Au+Au collisions at 11.6A GeV/c are characterized by two global observables: the energy measured near zero degrees (E{sub ZCAL}) and the total event multiplicity. Particle spectra are measured for different event classes that are defined in a two-dimensional grid of both global observables. For moderately central events ({sigma}/{sigma}{sub int}{lt}12{percent}) the proton dN/dy distributions do not depend on E{sub ZCAL} but only on the event multiplicity. In contrast the shape of the proton transverse spectra shows little dependence on the event multiplicity. The change in the proton dN/dy distributions suggests that different conditions are formed in the collision for different event classes. These event classes are studied for signals of new physics by measuring pion and kaon spectra and yields. In the event classes doubly selected on E{sub ZCAL} and multiplicity there is no indication of any unusual pion or kaon yields, spectra, or K/{pi} ratio even in the events with extreme multiplicity. {copyright} {ital 1999} {ital The American Physical Society}
122833143
E917 at the AGS: High Density Baryon Matter
Nuclear matter of high density is created during the collisions of Au+Au nuclei using the Alternating Gradient Synchrotron (AGS) located at Brookhaven National Laboratory.1, 2 Whether the formation of a quark-gluon plasma (QGP) occurs during these heavy-ion collisions, or even if it is possible to extract an unambiguous signal of its existence from the background of hadronic debris, remains highly speculative. Regardless of whether a QGP is created, the potential exists to do a great deal of interesting and exciting physics with the high density baryonic matter created during the Au+Au collisions at the AGS.
10335512
Antilambda production in Au+Au collisions at 11.7A GeV/c.
We present results for antilambda and antiproton production in Au+Au collisions at 11.7 A GeV/c including spectra and extracted invariant yields for both species in central and peripheral collisions in the rapidity range 1.0<y<1.4. The antilambda yield increases from dN(Lambda;)/dy = 1.2(+0.7+0.2)(-0.6-0.2)x10(-3) in peripheral collisions to 19(+4+3)(-5-2)x10(-3) in central collisions. The direct antiproton yield is deduced from the measured total antiproton spectra to extract the ratio of antilambda-to-direct-antiproton production. The Lambda/p ratio near midrapidity increases from 0.26(+0.19+0.5)(-0.15-0.4) in peripheral collisions to 3.6(+4.7+2.7)(-1.8-1.1) in central collisions, a value larger than current theoretical estimates.
18889238
Studies of the vector meson mass generation scheme by chiral anomalies in two-dimensional nonAbelian gauge theories
Higher order effects of the two-dimensional non-Abelian gauge theories, in which the vector-meson mass is generated by chiral anomalies, will be studied. The $\beta$ function and the topological nature of the non-linear $\sigma$ model in the action and unitarity of the theory will be discussed.
34566683
Sign of the neutron-proton mass difference in an SU(2) x U(1) supersymmetric toy model: A possible scenario for solving the old puzzle.
Based on the idea that electromagnetism is responsible for mass differences within isotopic multiplets (e.g., pointlike neutron and proton or {ital u} and {ital d} quarks), we generalize an SU(2){times}U(1) model in a toy field theory of vectors to a supersymmetric model and investigate the finite mass difference within the isotopic doublet. It is found that under soft-supersymmetry breaking, a positive {ital n}-{ital p} mass difference can be obtained under reasonable assumptions for the parameters involved.
17524844
Measuring the hadronic cross-section at KLOE using the radiative return
We present a study of the reaction e+e−→π+π−γ at theφ peak with the KLOE detector at the φ–factory DAΦNE. This reaction allows us to obtain the cross section for e+e−→π+π− from theee center-of-mass energy W = mφ = 1019 MeV down to threshold, i.e.2mπ < Mππ < mφ. This is called radiative return. The status of the analysis and preliminary results on the invariant mass spectrum of the two-pion-state are presented.
55942665
Slow, target associated particles produced in ultrarelativistic heavy-ion interactions
Abstract The slow, target associated particles produced in ultrarelativistic heavy-ion interactions are a quantitative probe of the cascading processes in the spectator parts of the target nucleus. These processes are directly influenced by the proper timescale for the formation of hadronic matter. In this letter we show experimental data on singly and multiply charged particles, with velocities smaller than 0.7 c , produced in ultrarelativistic heavy-ion interactions in nuclear emulsion.
119189783
Measurement of the charged kaon lifetime with the KLOE detector
We have measured the charged kaon lifetime using a sample of 15 × 106 tagged kaon decays. Charged kaons were produced in pairs at the DAΦNE -factory, e+e− → → K+K−. The decay of a K+ was tagged by the production of a K− and viceversa. The lifetime was obtained, for both charges, from independent measurements of the decay time and decay length distributions. From fits to the four distributions we find τ = (12.347±0.030) ns.
209835401
Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton–proton collision data with the ATLAS detector
A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ...
197468931
Study of jet shapes in inclusive jet production in pp collisions at sqrt[s]=7 TeV using the ATLAS detector
Jet shapes have been measured in inclusive jet production in proton-proton collisions at sqrt(s) = 7 TeV using 3 pb^{-1} of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeV < pT < 600 GeV and rapidity in the region |y| < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and non-perturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.