A search for the exotic Ξ<Superscript>−−</Superscript> (1860) in the hyperon beam experiment WA89(1860) in the hyperon beam experiment WA89

We report on a high statistics search for the Ξ^??(1860) resonance in Σ^?-nucleus collisions at 340 GeV/c. No evidence for this resonance is found in our data sample which contains 676000 Ξ^? candidates above bakground. For the decay channel Ξ^??(1860)→Ξ^? π ^? and the kinematic range 0.15<xF<0.9 we find a 3σ upper limit for the production cross section of 3.1 and 3.5 μb per nucleon, for reactions with carbon and copper, respectively.     

Calibration and evaluation of optical systems for full-field strain measurement

The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards.     

Hochgradige Einschlussthermometer

Ohne Zusammenfassung     

First observation ofΩ * resonances

In a experiment at the CERN SPS charged hyperon beam using incident Ξ^?, we have obtained evidence for the production of two Ω^* resonances decaying into Ξ^?π⁺ K ^?, with the following parameters:M ₁=2251±12,Γ ₁=48±20 MeV/c², 78 ±23 events, andM ₂=2284±12,Γ ₂=26±23 MeV/c² 45±10 events. The first state is also observed as a 4.2σ effect in a subsample which contains an additionalK ⁺ orK ⁰ in the final state. Production cross sections and branching ratios to Ξ^* K ^? and Ξ^? K ^* are presented.     

A double-pass optical parametric amplifier seeded by a blue-shifted output of a photonic-crystal fiber

A blue-shifted output of a photonic-crystal fiber, providing a frequency upconversion of femtosecond Ti:sapphire laser pulses, is used to seed a double-pass optical parametric oscillator (OPA). The OPA is based on a BBO crystal, pumped by 65-mW 150-fs second-harmonic pulses of a Ti:sapphire laser. Gain factors in excess of 10³ are demonstrated for such an OPA, yielding tunable light pulses within the range of wavelengths from 420 to 650 nm, a peak power up to 250 kW, and a typical pulse width of about 200 fs at a repetition rate of 100 kHz. PACS 42.81.Gs; 42.81.Qb