H. Ozaki

A study of K−π+ scattering in the reaction K−p→K−π+n at 11 GeV/c

Results from a high statistics study of the reaction K−p→K−π+n are presented. These results are based on data obtained with an 11 GeV/c beam using the LASS spectrometer at SLAC. The mass dependence of the spherical harmonic moments provides clear evidence for the production of the complete leading orbitally excited K∗ series up through JP = 5−. These moments are used to perform an energy independent partial wave analysis of the K−π+ system from threshold to 2.6 GeV/c2 using a t-dependent parametrization of the production amplitudes. The amplitudes corroborate the leading K∗(892), K2∗(1430), K3∗(1780), K4∗(2060), and K5∗(2380) resonances observed directly in the moments, and also provide new evidence for underlying states. The 0+ amplitude contains the K0∗(1350) and a second 0+K∗(1950) at higher mass. The 1−K∗(1790) seen earlier two and three-body analyses is confirmed, and evidence is provided for suppressed K−π+ decay mode of a second 1− state, the K∗(1410), which has been seen in earlier three-body analyses.

A study of the Ks0Ks0 system in the reaction K−p→Ks0Ks0Λ at 11 GeV/c

Abstract A 4.1 event/nb sample of 11 GeV/c K−p interactions in the LASS spectrometer at SLAC has been used in an analysis of the exclusive Ks0Ks0Λ final state. The Ks0Ks0 mass distribution exhibits a small cluster of events near threshold, but the mass spectrum is dominated by the f2′(1525), which an amplitude analysis shows to be produced by both natural and unnatural parity exchange. This analysis also provides evidence for an S-wave state in the f2′(1525) region, while production of the f2(1720) is not observed. However, there is structure at ∼ 2.2 GeV/c2 which is similar in shape to that observed in the region of the X(2220) in radiative J/ψ decay; an analysis of the angular distribution indicates a spin of at least 2 in this region. This, together with results from other analyses, indicates that the X(2220) may be the 2++ or 4++, mainly s s , state expected near this mass in the conventional quark model.

A gas sampling electromagnetic calorimeter using conductive plastic tubes

A prototype of gas sampling electromagnetic calorimeter with conductive plastic tubes was studied under practical conditions. An energy resolution of σEE = 20.4(E(GeV))−12 (%) was obtained in the few-GeV region and the spatial resolu for 4 GeV electrons was σx = 5.4 mm for pads and σx = 2.2 mm for strips. No appreciable effect on the energy resolution was found by magnetic field of 1 kG applied perpendicularly to the anode wire.

Evidence for two strangeonium resonances with JPC=1++ and 1+− in K−p interactions at 11 GeV/c☆

Abstract The results of a partial wave analysis of the low mass KKπ system produced in the reactions K − p →K 0 s K ± π ± Λ at 11 GeV/ c using the LASS spectrometer are presented. Evidence is given for two ss axial-vector meson states: one with quantum numbers J PC = 1 ++ , mass ∼ 1530 MeV/ c 2 , and width ∼ 100 MeV/ c 2 , and the other with quantum numbers J PC =1 +− , mass ∼ 1380 MeV/ c 2 , and width ∼ 80 MeV/ c 2 . These states are good candidates to be the mostly strangeonium members of the ground state 1 ++ and 1 +− nonets predicted by the quark model.

Search for SUSY Particles in e+ e- Annihilation at Tristan

Abstract The TOPAZ detector has accumulated about 11 pb−1 of data in the energy range s =52−57 GeV . Charged supersymmetric particles have been searched for. Assuming the photino to be massless, we place limits on the chargino of m χ GeV , on the scalar muon, tau, and quark of m μ GeV , m τ GeV , and m q GeV . The scalar electron can be excluded up to a mass of ∼ 28 GeV. Other cases are examined.

A cathode readout gas sampling calorimeter with conductive plastic tubes

Abstract We constructed and tested a prototype gas sampling electromagnetic calorimeter of the Pb-proportional tube sandwich type. The calorimeter uses conductive plastic tubes and cathode pad readout with a tower structure which resulted in reasonable energy and spatial resolutions for electrons in the momentum range 0.5–4.0 GeV/c; σ E E = 21% (E( GeV ) ) 1 2 , σ x = 6 mm (at 3 GeV /c). This paper describes the test and the performance studied under various conditions.

The strange meson resonances observed in the reaction K−p → K0π+π−n at GeV/c

Abstract A model incorporating K ∗ resonance contributions and simple backgrounds is shown to quantitatively reproduce the mass dependence of the partial wave amplitudes governing the production and decay of the K 0 π + π − system. A fit of this model to these amplitudes confirms the resonance interpretations of the well-established 1 + K 1 (1400), the 2 + K 2 ∗ (1430), the 3 − K 3 ∗ (1780), and the less well-known 1 − states, the K ∗ (1410) and the K ∗ (1790). The 4 + amplitudes are shown to be consistent with the production and decay of the 4 + K 4 ∗ (2060). A second 2 + enhancement at a mass of ∼ 1.95 GeV/ c 2 can be interpreted as resonant and may be the radial excitation of the K 2 ∗ (1430) or the triplet partner of the K 4 ∗ (2060). New measurements of the masses, widths and branching ratios of these states are given, and the implications of these data for the spectroscopy of the non-strange meson sector are discussed.

Study of limited streamer drift tube performance

Abstract We have studied the performance of limited streamer drift tubes made of conductive plastic. Spatial resolution and rate capability obtained are 100–150 μm and 2–3 kHz/cm, respectively.

The Strange Meson Resonances Observed in the Reaction

Abstract A model incorporating K ∗ resonance contributions and simple backgrounds is shown to quantitatively reproduce the mass dependence of the partial wave amplitudes governing the production and decay of the K 0 π + π − system. A fit of this model to these amplitudes confirms the resonance interpretations of the well-established 1 + K 1 (1400), the 2 + K 2 ∗ (1430), the 3 − K 3 ∗ (1780), and the less well-known 1 − states, the K ∗ (1410) and the K ∗ (1790). The 4 + amplitudes are shown to be consistent with the production and decay of the 4 + K 4 ∗ (2060). A second 2 + enhancement at a mass of ∼ 1.95 GeV/ c 2 can be interpreted as resonant and may be the radial excitation of the K 2 ∗ (1430) or the triplet partner of the K 4 ∗ (2060). New measurements of the masses, widths and branching ratios of these states are given, and the implications of these data for the spectroscopy of the non-strange meson sector are discussed.

K^- p \to \bar{K}0 \pi^+ \pi^- n

Abstract A prototype of an automated monitoring and calibrating system of gas gain and electron drift velocity for the end cap detectors in TOPAZ [1] is constructed. Systematic data under various conditions of gas mixture, temperature, pressure and applied high voltage are accumulated using this system. They will be used as reference for a detailed calibration.