Dave Pellett

Two-photon production of KS0K±π∓ states has been studied by the TPC/Two-Gamma experiment at the SLAC storage ring PEP. A resonance of mass 1.42 GeV was seen when one of the photons was quite virtual but not when both photons were nearly real. Production of a spin-1 meson, which cannot be made by two real photons, would fit these observations. The Q2 dependence of the data in the resonance region agrees with this spin assignment and is incompatible with a spin-0 hypothesis. The mass and width of the resonance are similar to those of the E meson, which has been assigned JP=0− and JP=1+ by different experiments.Received 14 August 1986DOI:https://doi.org/10.1103/PhysRevLett.57.2500©1986 American Physical Society

The total hadronic cross section for virtual photon-photon interactions is reported for center-of-mass energy, W, between 2 and 20 GeV. The data were obtained via the process ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\gamma}}^{\mathrm{*}}$${\ensuremath{\gamma}}^{\mathrm{*}}$\ensuremath{\rightarrow}e $^{+}e^{\mathrm{\ensuremath{-}}}$+hadrons with both scattered ${e}^{+}$ and ${e}^{\mathrm{\ensuremath{-}}}$ detected. Each photon's four-momentum squared, ${q}^{2}$, ranges from -0.1 to -1.6 ${\mathrm{GeV}}^{2}$. Dependence upon ${q}^{2}$ agrees with a generalized vector-meson-dominance model. The total cross section shows little W dependence, averaging 125 nb at ${q}_{1}^{2}$=${q}_{2}^{2}$=-0.3. Photon helicity interference terms are determined.

We present a measurement of the total cross section for γγ→hadrons, with one photon quasireal and the other a spacelike photon of mass squared −Q2. Results are presented as a function of Q2 and the γγ center-of-mass energy W, with the Q2 range extending from 0.2 to 60 GeV2, and W in the range from 2 to 10 GeV. The data were taken with the TPC/Two-Gamma facility at the SLAC e+e− storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle falloff with increasing W. Its Q2 dependence is shown to be well described by an incoherent sum of vector-meson and pointlike scattering over most of the observed W range. Agreement at high Q2 is improved if a minimum-pT cutoff (motivated by QCD) is imposed on the pointlike contribution.Received 11 September 1989DOI:https://doi.org/10.1103/PhysRevD.41.2667©1990 American Physical Society

We report on the production of J/psi mesons in 530 and 800 GeV/c proton - Be collisions in the Feynman-x range 0.0 < xf < 0.6. The J/psi mesons were detected via decays into opposite sign muon pairs. Differential distributions for J/psi production have been measured as functions of xf, pT^2, and cosine of the Gottfried-Jackson decay angle. These distributions are compared with results on J/psi production obtained in 515 GeV/c pion - Be collisions, measured by the same experiment, as well as with results from other experiments using incident protons.

The TPC/Two-Gamma Collaboration has measured the inclusive cross section for production of charmed D∗± mesons in photon-photon collisions. The reaction utilized was e+e-→e+e-D∗±X, with D∗±→DOπ+-, DO→K-+π ±, and either zero or one outgoing e± detected. The result, σ(e+e- → e+e-D∗±X) = 74±26±19 pb, is in agreement with the quark parton mo del prediction for e+e- → e+e-cc, combined with a Lund model for the hadronization of the charmed quarks.

We report here on preliminary results obtained from observing the reactions π− + LiH → μ+ + μ− + …π− + LiH → π+ + π− + … using 11.2 GeVc incident π− mesons from the CERN Proton Synchroton. From these reactions we have determined the branching ratio Γ(ρ → μμ) Γ(e → ππ).

We measure an inclusive branching fraction of (13.9 ± 2.0+1.9−2.2)% for the decay τ−→ντπ−π0+nh0(n>~1), where h0 is a π0 or an η. The data sample, obtained with the time-projection-chamber detector facility at the SLAC e+e− storage ring PEP, corresponds to an integrated luminosity of 72 pb−1 at 29 GeV center-of-mass energy. The measured branching fraction is somewhat greater than the theoretical prediction and, with errors taken into account, could resolve the present difference between the inclusive and the sum of the exclusive τ± branching fractions into one charged prong.Received 1 July 1986DOI:https://doi.org/10.1103/PhysRevLett.57.1836©1986 American Physical Society

Abstract A new silicon microstrip detector was designed by the CDF collaboration for the proposed high-luminosity operation of the Tevatron p p ¯ collider (Run IIb). The detector is radiation-tolerant and will still be functional after exposure to particle fluences of 10 14 1 - MeV equivalent neutrons / cm 2 and radiation doses of 20 MRad. The detector will maintain or exceed the performance of the current CDF silicon detector throughout Run IIb. It is based on an innovative silicon “supermodule” design. Critical detector components like the custom radiation-hard SVX4 readout chip, the beryllia hybrids and mini-port (repeater) cards, and the silicon sensors fulfill their specifications and were produced with high yields. The design goals and solutions of the CDF Run IIb silicon detector are described, and the performance of preproduction modules is presented in detail. Results relevant for the development of future silicon systems are emphasized.

The energy dependence of the cross section for reactions ${K}^{+}n\ensuremath{\rightarrow}{K}^{*}(890)p$ and ${K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}^{*}(890)n$ is compared over a wide range of incident momenta and found to be identical. This excludes odd $C$-parity exchanges in addition to the dominant $\ensuremath{\pi}$ exchange. The conventional absorption model does not reproduce the rapid decrease of ${\ensuremath{\rho}}_{00}$ as a function of the four-momentum transfer. The Reggeized $\ensuremath{\pi}\ensuremath{-}{A}_{2}$ model of Dass and Froggatt reproduces the $t$ dependence of ${\ensuremath{\rho}}_{00}$ and $\mathrm{Re}{\ensuremath{\rho}}_{10}$, but there is serious disagreement for ${\ensuremath{\rho}}_{1\ensuremath{-}1}$ which may indicate the need to include ${A}_{1}$ exchange. The asymmetry in the decay angular distribution is interpreted as $S\ensuremath{-}P$ wave interference.

We have observed ${K}^{*}(1760)$ and ${K}^{*}(2100)$ production in a 10-event/\ensuremath{\mu}b ${K}^{+}d$ experiment at 9 GeV/c. The ${K}^{*}(1760)$ has a mass of 1769 \ifmmode\pm\else\textpm\fi{} 12 MeV and a width of 132 \ifmmode\pm\else\textpm\fi{} 50 MeV and the ${K}^{*}(2100)$ has a mass of 2115 \ifmmode\pm\else\textpm\fi{} 46 MeV and a width of 300 \ifmmode\pm\else\textpm\fi{} 200 MeV. Branching ratios for decay into various final states are presented and evidence for decay into two, three, and four scalar mesons is presented. The spin-parity of the ${K}^{*}(1760)$ is found to be ${3}^{\ensuremath{-}}$. The ${K}^{*}(2100)$ is compatible with a ${4}^{+}$ assignment.

We present results on the production of high transverse momentum pizero and eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75 in rapidity. The inclusive pizero cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.

We have measured the polarization of ${D}^{*}$, the energy dependence of the polarization, and the spin-density matrix of ${D}^{*}$ in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at a center-of-mass energy of 29 GeV using the Time Projection Chamber detector at the SLAC storage ring PEP. In 147 ${\mathrm{pb}}^{\ensuremath{-}1}$ of data we see no strong evidence for polarization, alignment, or final-state interactions in this fragmentation process.

We present results on the production of direct photons, pizero, and eta mesons on nuclear targets at large transverse momenta (p_T). The data are from 530 and 800 GeV/c proton beams and 515 GeV/c piminus beams incident upon copper and beryllium targets that span the kinematic range of 1.0 &lt; p_T &lt; 10 GeV/c at central rapidities.

The Intermediate Silicon Layers (ISL) detector is presently being built as part of CDF upgrades. The ISL is a large radius (28 cm) silicon tracker with a total active area of about 3.5 m2. The challenge is to build a device which provides precise 3D points introducing a minimal amount of material for the supporting structure. The design and the status of the project are described.

Author(s): Alston-Garnjost, M.; Avery, R.E.; Barker, A.R.; Bauer, D.A.; Bay, A.; Buijs, A.; Belcinski, R.; Bingham, H.H.; Bloom, E.D.; Buchanan, C.D.; Caldwell, D.O.; Chao, H-Y.; Chun, S-B.; Clark, A.R.; Crane, D.A.; Dahl, O.I.; Daoudi, M.; Eastman, J.J.; Eberhard, P.H.; Edberg, T.K.; Eisner, A.M.; Erne, F.C.; Fairfield, K.H.; Godfrey, G.; Hauptman, J.M.; Hofmann, W.; Kenney, R.W.; Khacheryan, S.; Knopfle, K.T.; Kofler, R.R.; Lambert, D.J.; Langeveld, W.G.J.; Layter, J.G.; Lin, W.T.; Linde, F.L.; Loken, S.C.; Lu, A.; Lynch, G.R.; Lys, J.E.; Madaras, R.J.; Marsiske, H.; Masek, G.E.; Loken, S.C.; Lu, A.; Lynch, G.R.; Lys, J.E.; Madaras, R.J.; Marsiske, H.; Masek, G.E.; Mathis, L.G.; Miller, E.S.; Nicol, N.A.; Nygren, D.R.; Oddone, P.J.; Oyang, Y.-T.; Paar, H.P.; Palounek, A.P.T.; Park, S.K.; Pellett, D.E.; Pripstein, M.; Ronan, M.T.; Ross, R.R.; Sens, J.C.; Shapiro, G.; Shen, B.C.; Steinman, J.S.; Stephens, R.W.; Stevenson, M.L.; Stork, D.H.; Strauss, M.G.; Sullivan, M.K.; Toutounchi, S.; Vernon, W.; Wang, E.M.; Wang, Y.-X.; Wenzel, W.A.; Yamamoto, H.; Yellin, S.J.; Yost, G.P.; Zapalac, G.; Zeitlin, C.

In this paper we present a description of a three-view segmented hadron calorimeter which provides three dimensional information on shower location as well as the usual energy deposition. We summarize several important results emerging from the use of our hadron calorimeter both as a component of an hybrid bubble chamber trigger and in the data reduction and analysis. Calibration data taken during our run cycle allowed determination of the spatial and energy resolution of the calorimeter as a function of the shower distribution and incident particle energy. Also an algorithm was developed which permitted good determination of the shower trajectory and errors even for showers not fully contained within the calorimeter and thereby indicating a significant loss of energy deposition.

We present results on the production of high transverse momentum charm mesons in collisions of 515 GeV/c negative pions with beryllium and copper targets. The experiment recorded a large sample of events containing high transverse momentum (p{sub T}) showers detected in an electromagnetic calorimeter. From these data, a sample of charm mesons has been reconstructed via their decay into the fully charged K{pi}{pi} mode. A measurement of the single inclusive transverse momentum distribution of charged D mesons from 1 to 8 GeV/c is presented. An extrapolation of the measured differential cross section yields an integrated D{sup {plus_minus}} cross section of 11.4{plus_minus}2.7(stat){plus_minus}3.3(syst) {mu}b per nucleon for D{sup {plus_minus}} mesons with x{sub F}{gt}0. The data are compared with expectations based upon next-to-leading-order perturbative QCD, as well as with results from PYTHIA. We also compare our integrated D{sup {plus_minus}} cross section with measurements from other experiments. {copyright} {ital 1997} {ital The American Physical Society}

A search for SU(3) manifestly exotic ${Q}^{2}$Q\ifmmode\bar\else\textasciimacron\fi{} $^{2}$ baryonium states in antiproton-deuterium interactions was carried out at the SLAC 40-in. hybrid bubble-chamber facility. The I=(3/2, S=1 channel, ${X}^{\mathrm{\ensuremath{-}}}$, produced in conjunction with a forward produced neutral antikaon was studied. Such ${X}^{\mathrm{\ensuremath{-}}}$ states would decay into an antihyperon and a baryon. The fast forward K\ifmmode\bar\else\textasciimacron\fi{} $^{0}$ was detected in a three-view segmented calorimeter placed downstream of the bubble chamber and used as part of the trigger. Upper limits of 0.50--1.63 \ensuremath{\mu}b are reported for the ${X}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}\ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{}n${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, \ensuremath{\Sigma}\ifmmode\bar\else\textasciimacron\fi{} $^{\mathrm{\ensuremath{-}}}n$, \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{}p${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, \ensuremath{\Sigma}\ifmmode\bar\else\textasciimacron\fi{} $^{\mathrm{\ensuremath{-}}}\ensuremath{\pi}^{\mathrm{\ensuremath{-}}}$, \ensuremath{\Sigma}\ifmmode\bar\else\textasciimacron\fi{} $^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\pi}^{\ensuremath{\mp}}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ exclusive channels based upon \ensuremath{\le}13 events per channel.