Total Transverse Energy Research Articles

Some remarks on reducibility and thermal scaling in nuclear fragmentation

The relationship between fragment multiplicity NI M F and total transverse energy Et in nuclear fragmentation is studied with help of simple analytical considerations. It is suggested that the recent claim about reducibility and thermal scaling is due to an auto-correlation between Et and p the elementary probability deduced from the binomial-like behaviour of NI M F.

Central collisions of Au on Au at 150, 250 and 400 A·MeV

Collisions of Au on Au at incident energies of 150, 250 and 400 A·MeV were studied with the FOPI-facility at GSI Darmstadt. Nuclear charge ( Z ⩽ 15) and velocity of the products were detected with full azimuthal acceptance at laboratory angles 1° ⩽ θlab ⩽ 30°. Isotope separated light charged particles were measured with movable multiple telescopes in an angular range of 6–90°. Central collisions representing about 1% of the reaction cross section were selected by requiring high total transverse energy, but vanishing side flow. The velocity space distributions and yields of the emitted fragments are reported. the data are analysed in terms of a thermal model including radial flow. A comparison with predictions of the quantum molecular model is presented.

First Evidence of Directed Flow at 158 A GeV Pb + Pb Collisions in WA98 Experiment

The first evidence of directed flow at 158 A GeV Pb + Pb collisions is observed using the Plastic Ball detector in WA98 experiment. The azimuthal angle of the total transverse energy, Phi(o), is determined for each event using the observed protons in the Plastic Ball. A clear azimuthal asymmetry of fragments is observed with respect to Phi(o). The degree of azimuthal asymmetry is found to be largest in mid-central collisions, which is consistent with the picture of the collective flow. The p(t) spectra of particles measured in the mid-rapidity spectrometer has been studied in conjunction with the Plastic Ball, and different p(t) slopes with respect to Phi(o) for proton and pi(+) are observed.

Transverse energy production in 208Pb+Pb collisions at 158 GeV per nucleon.

Author(s): Margetis, S.; Alber, T.; Appelshauser, H.; Bachler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gasdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuhmichel, A.; Lsdiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.J.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puhlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, Hans G.; Rohrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schafer, E.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the γp centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.

The ZEUS calorimeter first level trigger

The design of the ZEUS Calorimeter First Level Trigger (CFLT) is presented. The CFLT utilizes a pipelined architecture to provide trigger data for a Global First Level Trigger decision 5 μs after each beam crossing, occurring every 96 ns. The charges from 13 K phototubes are summed into 1792 trigger tower pulseheights which are digitized by flash ADCs. The digital values are linearized, stored and used for sums and pattern tests. Summary data is forwarded to the Global First Level Trigger for each crossing 2 μs after the crossing occurred. The CFLT determines the total energy, the total transverse energy, the missing energy, and the energy and number of isolated electrons and muons. It also provides information on the electromagnetic and hadronic energy deposited in various regions of the calorimeter. The CFLT has kept the experimental trigger rate below ≈ 200 Hz at the highest luminosity experienced at HERA. Performance studies suggest that the CFLT will keep the trigger rate below 1 kHz against a rate of proton-beam gas interactions on the order of the 100 kHz expected at design luminosity.

Detecting nuclear multifragmention

A moment analysis in terms of bivariate distributions of global variables for two colliding nuclei at intermediate energy is presented. It is shown that the selection of the impact parameter through narrow cuts in the total transverse kinetic energy naturally modifies the true fluctuations of the fragment multiplicity distributions. This is supported by a classical simulation of a system whose equation of state resembles that of nuclear matter. An intermittent behaviour of two colliding nuclei at a beam energy around 100 MeV/nucleon and large impact parameters is suggested.

First results with the Au-beam at the AGS

The first measurements using 11.6 A.GeV/c 197Au beam have been made in April 1992 at the Tandem-Booster-AGS accelerator facilities. Preliminary results from different experiments are presented for Au + Au collisions. Experiment E-877 shows a large increase of the total transverse energy between Si + Al and Au + Au reactions. Experiment E-866 observes an increase of the K+/π+ ratio (0.25 ± 0.02) with respect the Si + Au ratio.

Impact-parameter filters for 36Ar+ 197Au collisions at [formula omitted

Collisions between 36Ar projectiles and 197Au target nuclei at E A = 50, 80 and 110 MeV have been studied with the MSU Miniball, a 4 π phoswich array with a low detection threshold. Various impact-parameter filters, based upon total charged-particle multiplicity, transverse energy, midrapidity charge and multiplicity of emitted hydrogen nuclei, are compared and cross-correlated. The relative selectivity of each prescription for small impact-parameter collisions is evaluated by assessing the suppression of fast-particle emission at forward angles.

Fluctuations in multifragment decays

An analysis of charged particle distributions is performed to search for large fluctuations and signals of intermittency in 36 Ar+ 197 Au reactions at E/ A=35–110 MeV. When the effects of impact-parameter averaging are reduced by appropriate cuts on the total transverse energy, charged particle multiplicity distributions narrower than Poisson distributions are observed. Such distributions are inconsistent with intermittency signals of non-trivial origin.

Properties of events with large total transverse energy produced in proton-antiproton collisions at sqrt s =1.8 TeV.

The properties of proton-antiproton interactions in which the total transverse energy exceeds 400 GeV are described. These events have been recorded at the Fermilab Tevatron collider operating at a center-of-mass energy of 1.8 TeV. The differential cross section, jet rates, jet transverse-momentum and pseudorapidity distributions, single-jet shapes, and the multijet rates and kinematics are compared with QCD predictions. There is no evidence for a significant deviation from standard-model expectations that would be signaled by the presence of an excess of isolated high-transverse-momentum leptons or photons, or an excess of events with unusual jet rates or characteristics.

INITIAL STATE SCATTERING AND pT SPECTRA OF MUON PAIRS IN HADRON-NUCLEUS AND NUCLEUS-NUCLEUS COLLISIONS AT HIGH ENERGIES

The muon pair production processes in hadron-nucleus and nucleus-nucleus collisions at high energies are considered using the additive quark model and the perturbation QCD. The transverse momentum dependence of the muon pairs in hadron-nucleus collisions is described. The pT-dependence of the muon pair distributions and their ratio at different values of the total transverse energy ET in heavy nucleus collisions is predicted. A good description of the ET-dependence of [Formula: see text] is provided.

Free energy and emittance growth in nonstationary charged particle beams

Charged particle beams that are not perfectly matched or centered when injected into a focusing channel (or accelerator) have a higher total transverse energy than the equivalent ideal stationary beam. The excess energy ΔE represents free energy that can cause emittance growth. A general relationship between the possible emittance growth and ΔE is derived, and analytical results are presented for nonuniform, mismatched, and off-centered beams.

Measurement of QCD jet broadening in pp-bar collisions at sqrt s =1.8 TeV.

A measurement of the QCD jet-broadening parameter {l angle}{ital Q}{sub {ital T}}{r angle} is described for high-{ital E}{sub {ital T}} jet data in the central calorimeter of the Collider Detector at Fermilab. This method involves the use of a global event parameter which is free from the ambiguities associated with the definition and separation of individual clusters. The parameter {ital Q}{sub {ital T}} is defined as the scalar sum of the transverse momentum perpendicular to the transverse thrust axis. Parton-level QCD predictions are made for {l angle}{ital Q}{sub {ital T}}{r angle} as a function of {ital E}{sub {ital T}}, the total transverse energy in the events, and suggest that a measurement would show a dependence on the running of the strong coupling constant {alpha}{sub {ital s}}. Comparisons are made to first-order QCD parton-level calculations, as well as to fully evolved and hadronized leading-log simulations.

Transverse energy dependence of dilepton production in nuclear collisions as a signature of quark-gluon plasma formation

The dependence of dilepton production on total transverse energy in nuclear collisions is proposed as a signature of quark- gluon plasma formation. In particular the ratio of dilepton production in central (large transverse energy) to that in peripheral (low transverse energy) gives information about the presence of hydrodynamical space-time evolution of the quark-gluon plasma or of a mixed phase.

A study of the general characteristics of proton-antiproton collisions at √ s=0.2 to 0.9 TeV

The general characteristics of inelastic proton-antiproton collisions at the CERN SPS Collider are studied with the UA1 detector using magnetic and calorimetric analysis. Results are presented on charged particle multiplicities and transverse and longitudinal momenta, and on total transverse energy distributions at centre of mass energies ranging from 0.2 to 0.9 TeV.

Dependence ofJ/Ψ suppression in heavy ion collisions on total transverse energy, nucleon numbers andJ/Ψ transverse momentum

We present a set of semiquantitative predictions for the behaviour ofJ/Ψ suppression in heavy ion collisions as a function of the total transverse energy, nucleon numbers of colliding ions and theJ/Ψ transverse momentum. These predictions are based on the assumption that all ofJ/Ψ suppression is due toJ/Ψ and χ disintegrations in collisions with hadrons in a dense hadronic gas formed in the heavy ion collisions. The hydrodynamic evolution of the hadron gas is taken into account. The onset of the quarkgluon plasma formation should manifest itself by clear qualitative deviations fromJ/Ψ suppression calculated in this way, in particular as thresholds or kinks in theE T -dependence, or as a threshold forJ/Ψ suppression as a function of the atomic number of the target, expected a Cu or below.

Fourth-generation-quark production at the Superconducting Super Collider.

The production of fourth-generation quarks at the Superconducting Super Collider is studied concentrating on event signatures resulting from the single-lepton and two-lepton decay modes. We find that events with multijets (${n}_{\mathrm{jet}\ensuremath{\ge}3}$) and one or two high-${p}_{T}$ leptons are good signals for heavy-quark production for quark masses up to 600 GeV. In addition, we also found that the total transverse energy of an event is useful for distinguishing between heavy-quark production and the top-quark background.

The transverse energy distribution in16O-nucleus collisions at 60 and 200 GeV per nucleon

Transverse-energy distributions have been measured in the pseudorapidity region −0.1<η lab<2.9 for oxygen-nucleus collisions at incident energies of 60 and 200 GeV per nucleon for Al, Ag, and W target nuclei. The cross-section for the heaviest target nuclei at the highest incident energy is measured over 5 orders of magnitude and out to a maximumE T of 200 GeV. Measurements of the differential densitydE T/dη lab as a function ofη lab are presented. In the pseudorapidity region −0.1<η lab<2.9 the transverse energy for an average central collision is proportional to ≈A 0.5, while the fraction of the total transverse energy measured in an extended region ofη lab>2.9 decreases with increasingA. The distributions are compared with the predictions of a dual parton model. Finally the question of the energy density is addressed.

The transverse energy distribution in hadron-lead collisions

The transverse energy cross-sectiondσ/dE T has been measured in the pseudorapidity region 0.6<η<2.4 for hadron-lead collisions at 200 GeV/c incident hadron momentum. TheE T distribution extends to 40 GeV, which is twice the kinematic limit forp-p collisions at the same incident beam momentum. The distribution ofE T is found to shift towards low pseudorapidities with increasing total transverse energy.