The product ion rate o f electrons with momentum p > 4 G e V / c and large m o m e n t u m transverse to the jet containing the electron has been measured in 136 000 hadronic decays o f the Z ~ recorded with the O P A L detector at LEP in 1990. The dominan t source o f these electrons is the semileptonic decay of hadrons containing b quarks. I f we assume that the semileptonic branching fraction o f b hadrons produced on the Z ~ resonance is the same as the branching fraction measured at the r ( 4 S) resonance, we determine Fse = 394 + 13 + 32 MeV, where the first error is statistical and the second error is systematic. The sensitivity o f the result to this assumption is discussed. We have reduced the dependence o f our result on the model o f b hadron semileptonic decay by taking into account the correlat ion between the model dependence o f the branching fractions measured at the Y (4 S ) and of our kinematic acceptance for electrons.

Results are presented on a partial wave analysis of the omega eta final state produced in pi (-)p interactions at 18 GeV/e where omega --> pi (+)pi (-)pi (0), pi (0) --> 2 gamma, and eta --> 2 gamma. We observe the previously unreported decay mode omega (1650) --> omega eta and a new 1(+-) meson state h(1)(1595) with a mass M = 1594(+/-15)((+10)(-60)) MeV/c(2) and a width Gamma = 384(+/-60)((+70)(-100)) MeV/c(2). The h(1)(1595) state exhibits resonant-like phase motion relative to the omega (1650). (C) 2001 Elsevier Science B.V. All rights reserved.

New measurements of peripheral meson production are presented. The data confirm the existence of exotic mesons at 1.4 and 1.6 GeV/c2. The latter state dominates the eta'pi- decay spectrum. The data on eta pi+pi-pi- decay show large strength in several exotic (Jpc = 1- +) waves as well.

The mass and width of the a0(980) have been independently determined from a nearly background free data sample and the coupling constants to the eta-pi and K-K-bar modes have been determined

A partial-wave analysis of the reaction pi(-)p --> pi(+)pi(-)pi(-)p at 18 GeV/c has been performed on a data sample of 250 000 events obtained by Brookhaven experiment E852. The expected J(PC) = l(++)a(1)(1260), 2(++)a(2)(1320), and 2(-+)pi(2)(1670) resonant states are clearly observed. The exotic J(PC) = 1(-+) wave produced in the natural parity exchange processes shows distinct resonancelike phase motion at about 1.6 GeV/c(2) in the rho pi channel. A mass-dependent fit results in a resonance mass of 1593 +/- 8(-47)(+29) MeV/c(2) and a width of 168 +/- 20(-12)(+150) MeV/c(2).

A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in π p interactions. We describe the chamber's design considerations, details of its construction, electronics, and performance characteristics.

A 3045 element lead glass calorimeter and an associated fast trigger processor have been constructed, tested and implemented in BNL experiment E852 in conjunction with the multi-particle spectrometer (MPS). Approximately, 109 all-neutral and neutral plus charged triggers were recorded with this apparatus during data runs in 1994 and 1995. This paper reports on the construction, testing and performance of this lead glass calorimeter and the associated trigger processor.

The recent search for non q q̅ mesons in π^-p interactions at Brookhaven National Laboratory is summarized. Many final states such as ηπ, η' π^-, a_0π, f_1π, a_2π, b_1π, which are favored decay modes of exotics, are under investigation.

The design, construction, and performance of a 198-element CsI detector built for Brookhaven experiment E852 is described. Design considerations for the array included such factors as rate, magnetic field, sensitivity and acceptance. Signals were obtained with a photodiode/preamplifier combination using PIN photodiodes. Data were taken over the course of two runs during the summers of 1993 and 1994. A calibration procedure using halo muons is described. The gain, energy resolution, and position resolution of the detector are discussed. Finally, the ability of the detector to be used as a low energy photon veto is illustrated using the data.

A scintillation detector meeting specific physics requirements and geometrical constraints is described. It operates with high efficiency inside a 1 T magnet in an intense charged particle beam of up to 3 × 106 particles/s. It uses a unique light collection system combining air space, wavelength shifter disc and conventional lucite light guides. The detector is used in a veto mode to identify interactions that produce an all-neutral final state. The details of the counter's design, construction and performance are described.

Two prototype lead glass calorimeters have been constructed and tested at the AGS at Brookhaven National Lab. The first is a 25-element prototype (P1)

Using a sample of 5558 Z0 --> tau+-tau- decays produced at LEP a direct test of CP-invariance in the neutral current reaction e+e- --> tau+-tau- is performed. Samples of events where each tau-decays into a single charged particle have been isolated for the construction of CP-odd observables. Three different event classes are considered: lepton-lepton, lepton-hadron, and hadron-hadron. No evidence for a non-zero expectation value of the considered CP-observables and hence for CP-violation is observed. Quantitatively, we deduce from this null result an estimate on the weak dipole moment d(tau) (m(Z)2) = (-4.5 +/- 5.3 +/- 1.4) x 10(-17) e cm for the lepton-lepton signature and d(tau) (m(Z)2) = 1.4 +/- 3.7 +/-1.3) x 10(-17) e cm for the hadron-hadron signature. Combining these results we place a limit with 95% confidence of \d(tau)\ less-than-or-equal-to 7.0 x 10(-17) e cm.