P. van Hal

Intermittency patterns in π+p and K+p collisions at 250 GeV/c

Abstract Intermittent behaviour is observed in π + p and K + p collisions at 250 GeV/ c . It is stronger there than in O 16 emulsion, but weaker than in e + e − collisions. A jet cascading mechanism is, therefore, the most likely interpretation. Presently used fragmentation models do not (fully) reproduce the effect, suggesting that an improvement of the hadronization picture is needed.

Cross sections and charged multiplicity distributions for π+p,K+p andpp interactions at 250 GeV/c

Cross sections and charged multiplicity distributions for π+p,K+p andpp interactions at 250 GeV/c are presented and compared to each other as well as to earlier (for π+p andK+p lower energy) data. Consistently, the meson-proton (M+p) data have narrower multiplicity distributions and higher average multiplicity thanpp data. Up to our energy, generalized KNO functions describe the energy dependence of the shape of the multiplity distribution with one parameter forM+p and one forpp collisions. If interpreted in terms of negative binomials, the parameter 1/k tends to be slightly lower forM+p than forpp data. For both types of hadron-hadron collision, 1/k is larger than fore+e− andlp collisions.

Maximum particle densities in rapidity space of π+ p, K+ p and pp collisions at 250 GeV/c

Abstract In a study of π + p, K + p and pp collisions at √ s =22GeV in the european hybrid spectrometer (EHS), the maximum charged particle density per given rapidity interval is found to rise linearly with charged particle multiplicity, independent of beam particle type and practically independent of energy between 22 and 900 GeV. An anomalous π + p event is found with ten particles within the very narrow rapidity interval Δy =0.098.

Systemic sclerosis and its pulmonary complications in the Netherlands An epidemiological study

The prevalence and incidence of systemic sclerosis (SSc) in The Netherlands is unknown. The same holds true for its leading causes of death: pulmonary fibrosis and pulmonary arterial hypertension (PAH), for which effective treatment options have recently become available. Objective: To establish the prevalence and incidence of SSc and its pulmonary complications. Methods: Detailed information on patients in the POEMAS registry, “Pulmonary Hypertension Screening, a Multidisciplinary Approach in Scleroderma”, consisting of 819 patients, was combined with a nationwide questionnaire. Results: By combining the two sources the prevalence of SSc was found to be 8.9 per 100 000 adults. The incidence was 0.77 patients per 100 000 per year. PAH was diagnosed in 9.9% of SSc patients. The prevalence of interstitial lung disease in SSc varied from 19% to 47% depending on the definition used. Conclusion: This study clarifies the epidemiology of SSc in The Netherlands and confirms the frequent occurrence of pulmonary complications, based on 654 cases. This can and will be studied further in the ongoing POEMAS study.

Charged particle production inK + p, π p andpp interactions at 250 GeV/c

New results are reported on inclusive charged particle production inK+p,π+p andpp collisions at 250 GeV/c. Inclusive longitudinal and transverse momentum spectra of positively and negatively charged particles are presented. Scaling in the fragmentation regions and scaling violation in the central c.m. region is investigated in detail. The topological pseudo-rapidity densities are shown to scale in the c.m. energy range from 22 to 900 GeV.

Rapidity dependence of negative and all-charged multiplicities in non-diffractive π+p and pp collisions at 250 GeV/c

Multiplicity distributions of all charged and of negative particles for non (single)-diffractive events in π+p and pp collisions at 250 GeV/c (s=22 GeV) are presented for various rapidity intervals. The data are well described by the negative binomial distribution. The π+p and pp data are different for full phase space, but similar for the central region. In the central region, the relation kch≈12 k− holds for all charged and negative multiplicities. This favours the interpretation in terms of cascade models above (partial) stimulated emission models.

Intermittency effects in π+p and K+p collisions at 250 GeV/c

Abstract Density fluctuations are studied in rapidity, pseudo-rapidity and azimuthal angle, as well as in two-dimensional distributions in rapidity and azimuthal angle. Evidence for intermittency, i.e. rise of factorial moments with increasing resolution, is found in all four distributions. Intermittency is stronger in two dimensions than in one, but the difference is smaller than would be expected from the production of “pencil jets”. Contrary to what would be expected from Bose-Einstein interference, no increase by a factor 2 is found in slope when the analysis is restricted to particles of identical charge.

Topological cross sections and charged particle multiplicities inpp interactions at 360 GeV/c

Using data obtained with EHS equipped with the Rapid Cycling Bubble Chamber (RCBC) exposed to a proton beam of 360 GeV/c, we calculate topological cross sections. We present in great detail the procedure and the techniques used to correct raw data. Finally, we give multiplicity moments and multiplicity correlations and we compare the values obtained in our experiment, together with data at other energies, with different models.

Phase space dependence of the multiplicity distribution in π+ andpp collisions at 250 GeV/c

AbstractThe charged particle multiplicity distribution has been studied for non-single-diffractive π+p andpp collisions at