Jacek Pniewski

The identification of a double hyperfragment

Abstract The detailed analysis is presented of an event which is interpreted as the mesonic cascade decay of a double hyperfragment produced by the capture of a Ξ− hyperon on a light emulsion nucleus. The most likely interpretations of the double hyperfragment are those in terms of either ΛΛBe10 or ΛΛBe11.

Excited states of light hypernuclei

The γ spectra obtained with K− mesons stopped in 6Li and 7Li targets exhibited a γ line at 1.09 MeV (intensities 0.14 ± 0.02% and 0.37 ± 0.04%, respectively) which could be identified as a hypernuclear line, and a second one at 1.42 MeV (intensities 0.10 ± 0.02% and 0.04 ± 0.04%, respectively), the assignment of which is less certain. The 1.09 MeV line and the 1.42 MeV line (if this latter is, in fact, a hypernuclear one) must both be due to γ transitions in hypernuclei with mass number four. The excitation energy of 1.09 MeV, ascribed in turn to either 4ΛH∗ or 4ΛHe∗He∗, was used to recalculate the parameters of the phenomenological potentials proposed by Herndon and Tang for the Λ-N s-state interaction.

Evidence for the existence of particle-unstable states of the Λ12C and Λ14N hypernuclei

Abstract Evidence is presented for the existence of particle-unstable states of the Λ12C and Λ14N hypernuclei produced by the absorption at rest of K− mesons in light emulsion nuclei.

Dispersion management in soft glass all-solid photonic crystal fibres

The development of all-solid photonic crystal fibres for nonlinear optics is an alternative approach to air-glass solid core photonic crystal fibres. The use of soft glasses ensures a high refractive index contrast (> 0.1) and a high nonlinear coefficient of the fibres. We report on the dispersion management capabilities in all-solid photonic crystal fibres taking into account four thermally matched glasses which can be jointly processed using the stack-and-draw fibre technique. We present structures with over 450 nm broadband flat normal dispersion and ultra-flat near zero anomalous dispersion below 5 ps/nm/km over 300 nm dedicated to supercontinuum generation with 1540 nm laser sources. The development of an all-solid photonic crystal fibre made of F2 and NC21 glasses is presented. The fibre is used to demonstrate supercontinuum generation in the range of 730–870 nm (150 nm) with flatness below 5 dB.

Energy transport in plasmon waveguides on chains of metal nanoplates

An interest in energy transport in 3D chains of metal nanoparticles is oriented towards future applications in nanoscale optical devices. We consider plasmonic waveguides composed of silver nanoplates arranged in several geometries to find the one with the lowest attenuation. We investigate light propagation of 500-nm wavelength along different chains of silver nanoplates of subwavelength length and width and wavelength-size height. Energy transmission of the waveguides is analysed in the range of 400–2000 nm. We find that chain of short parallel nanoplates guides energy better than two electromagnetically coupled continuous stripes and all other considered nonparallel structures. In a wavelength range of 500–600 nm, this 2-μm long 3D waveguide transmits 39% of incident energy in a channel of λ × λ/2 cross section area.

The identified ΛΛ-hypernuclei and the predicted H-particle

The existence of the H particle, the dihyperon predicted by Jaffe, would bring into question the existence of double hypernuclei. We review the two double hypernucleus events published in the literature. We include an independent report, hitherto unpublished, which was made on the ΛΛ10Be event in 1963 and clarifies the salient features of the event; this report reaffirms its published interpretation. We have made a simple calculation of the energy spectrum for Ξ- hyperons produced with K- beams in past emulsion experiments, with a result which accounts adequately for the paucity of reported double hypernucleus events. We outline a hybrid emulsion experiment that would locate Ξ- hyperon interactions efficiently and could thereby greatly improve our knowledge of double hypernuclei.

Frequency of the emission of 8Li, 8B and 9Li fragements from interactions of 9 GeV protons with heavy emulsion nuclei

Abstract About 200 hammer tracks from primary 9 GeV proton interactions with heavy emulsion nuclei were collected. Using a width measurement method and correcting the results for the inclined tracks we were able to separate the boron fragments from lithium fragments in 90–95% of all the events. A careful analysis of possible biases has been made in a sample of some 100 hammer tracks not limited in inclination. The energy spectrum of α particles from 8 Li decay was found and compared with other theoretical and experimental results. The full kinematical analysis of 9 Li decay and critical analysis of measurement data made it possible to draw conclusions concerning the method of identification and the relative frequency of emission of these fragments. The absolute frequency of emission of 8 Li fragments for different N h intervals was estimated.

On the binding energy of the 12λC(g.s.) hypernucleus

Abstract A renewed analysis of six, most probably 12 ΛC , events observed in emulsion is presented. The binding energy, B Λ , of this hypernucleus is estimated to be (10.80 ± 0.18) MeV. The ΔB Λ values for mirror hypernucleus pairs, ΔB Λ being the B Λ value of the hypernucleus with the smaller atomic number less that of the one with larger Z , seem to become more positive with increase in mass number.

Emission of 8Li fragments from interactions of 9 and 24 GeV protons with heavy emulsion nuclei

Abstract A full account of the work concerning 445 hammer tracks collected from 9 GeV and 24 GeV proton interactions with heavy emulsion nuclei is presented. The conditions of the routine work on hammer tracks are established. The frequency of emission of 8 Li fragments for different N h intervals was estimated. Taking into account the effect of the motion of the nucleus the velocity fluctuations and nuclear recoil resulting from the fragment emission, the angular distribution and the energy spectrum were compared with the results of evaporation theory. The values of the parameters T , V and β, representing the temperature, Coulomb barrier and average velocity of the emitting nucleus, were estimated on different assumptions. A high value of T and a low value of V were obtained.

Final-state interactions in the decay of the hypernucleus Λ9Li and a reappraisal of the binding energies of A=9 hypernuclei

Abstract The Λ 9 Li →π − + 9 Be ∗ →π − + p + 8 Li and Λ 9 B →π − + 9 C ∗ →π − + p + 8 B decay modes were investigated. The existence of an isospin - 3 2 state of 9Be, with excitation energy 18.6 ± 0.1 MeV and width Γ ≲ 300 keV has been established. From a reanalysis of European K− Collaboration emulsion data, new values of the binding energies of 9ΛLi and 9ΛB hypernuclei were found as 8.50 ± 0.12 MeV and 8.29 ± 0.18 MeV, respectively.