Pasożytnicze Isododa ryb Morza Czarnego

Praca prezentuje pasożytnicze Isopoda oraz gatunek Gnathia bacescoi w stadium pranizy, który jest nowo poznanym składnikiem fauny M. Czarnego. W słonawych wodach tego akwenu nastąpiła redukcja liczby gatunków pasożytniczych Isopoda w porównaniu z Morzem śródziemnym i Atlantykiem

Pasożytnicze Isododa ryb Morza Czarnego

Praca prezentuje pasożytnicze Isopoda oraz gatunek Gnathia bacescoi w stadium pranizy, który jest nowo poznanym składnikiem fauny M. Czarnego. W słonawych wodach tego akwenu nastąpiła redukcja liczby gatunków pasożytniczych Isopoda w porównaniu z Morzem śródziemnym i Atlantykiem

Stable and high quality electron beams from staged laser and plasma wakefield accelerators

We present experimental results on a plasma wakefield accelerator (PWFA) driven by high-current electron beams from a laser wakefield accelerator (LWFA). In this staged setup stable and high quality (low divergence and low energy spread) electron beams are generated at an optically-generated hydrodynamic shock in the PWFA. The energy stability of the beams produced by that arrangement in the PWFA stage is comparable to both single-stage laser accelerators and plasma wakefield accelerators driven by conventional accelerators. Simulations support that the intrinsic insensitivity of PWFAs to driver energy fluctuations can be exploited to overcome stability limitations of state-of-the-art laser wakefield accelerators when adding a PWFA stage. Furthermore, we demonstrate the generation of electron bunches with energy spread and divergence superior to single-stage LW-FAs, resulting in bunches with dense phase space and an angular-spectral charge density beyond the initial drive beam parameters. These results unambiguously show that staged LWFA-PWFA can help to tailor the electron-beam quality for certain applications and to reduce the influence of fluctuating laser drivers on the electron-beam stability. This encourages further development of this new class of staged wakefield acceleration as a viable scheme towards compact, high-quality electron beam sources

Production of Z⁰ bosons in elastic and quasi-elastic <i>ep</i> collisions at HERA

The production of Z&lt;sup&gt;0&lt;/sup&gt; bosons in the reaction ep→eZ&lt;sup&gt;0&lt;/sup&gt;p&lt;sup&gt;(⁎)&lt;/sup&gt;, where p&lt;sup&gt;(⁎)&lt;/sup&gt; stands for a proton or a low-mass nucleon resonance, has been studied in &lt;i&gt;ep&lt;/i&gt; collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb&lt;sup&gt;−1&lt;/sup&gt; of integrated luminosity. The Z&lt;sup&gt;0&lt;/sup&gt; was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on ηmax&lt;3.0, where η&lt;sub&gt;max&lt;/sub&gt; is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z&lt;sup&gt;0&lt;/sup&gt; mass. The cross section of the reaction ep→ eZ&lt;sup&gt;0&lt;/sup&gt;p&lt;sup&gt;(⁎)&lt;/sup&gt; was measured to be σ(ep→ eZ&lt;sup&gt;0&lt;/sup&gt;p&lt;sup&gt;(⁎)&lt;/sup&gt;)=0.13±0.06(stat.)±0.01(syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z&lt;sup&gt;0&lt;/sup&gt; production in &lt;i&gt;ep&lt;/i&gt; collisions

Measurement of Isolated Photons Accompanied by Jets in Deep Inelasic epep Scattering

The production of isolated high-energy photons accompanied by jets has been measured in deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 326 pb^{-1}. Measurements were made for exchanged photon virtualities, Q^2, in the range 10 to 350 GeV^2. The photons were measured in the transverse-energy and pseudorapidity ranges 4 < ET^gamma < 15 GeV and -0.7 < eta^gamma < 0.9, and the jets were measured in the transverse-energy and pseudorapidity ranges 2.5 < ET^jet <35 GeV and -1.5 < eta^jet < 1.8. Differential cross sections are presented as functions of these quantities. Perturbative QCD predictions give a reasonable description of the shape of the measured cross sections over most of the kinematic range, but the absolute normalisation is typically in disagreement by 20-30%.Comment: 17 pages, 4 figures. Minor changes in published versio