A. Bujak

Critical phenomena in hadronic matter and experimental isotopic yields in high energy proton-nucleus collisions

Abstract We present our experimental data for relative isotopic yields of nuclear fragments in high energy proton-nucleus collisions. When nuclear fragmentation is assumed to be droplet formation in a system near the critical point, the relative isotopic yields of 60 nuclear fragments in the mass range 12⩽Af⩽31 can be described by a simple thermodynamic model.

A high resolution muon detector

Abstract The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δp p = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

The role of double parton collisions in soft hadron interactions

Abstract We have examined charged multiplicities arising from p−p and p− p collisions over the range of center of mass energies, s , from 30 GeV to 1800 GeV. Results from Tevatron experiment E735 support the presence of double parton interactions. These processes can be seen to account for a large fraction of the increase in the non single diffraction inelastic cross section from energies of about 200 GeV to 1800 GeV.

Charged particle multiplicity correlations in pp̄ collisions at s=0.3−1.8 TeV

Abstract The correlations between charged particle multiplicitie produced in forward and backward pseudorapidity regions in pp interactions have been measured with a 240 element scintillator hodoscope. The correlation coefficient and the variance of the difference of multiplicities in the two pseudorapidity regions were deterermined for s =0.3−1.8 TeV . These results have been interpreted in terms of a cluster model of particle production.

Evidence for hadronic deconfinement in p̄–p collisions at 1.8 TeV

Abstract We have measured deconfined hadronic volumes, 4.4 V 3 , produced by a one-dimensional (1D) expansion. These volumes are directly proportional to the charged particle pseudorapidity densities 6.75 dN c / dη T =179.5±5(syst) MeV. Using Bjorkens 1D model, the hadronization energy density is ϵ F =1.10±0.26(stat) GeV/fm 3 corresponding to an excitation of 24.8±6.2(stat) quark–gluon degrees of freedom.

Charged particle multiplicity correlations in

Abstract The correlations between charged particle multiplicitie produced in forward and backward pseudorapidity regions in pp interactions have been measured with a 240 element scintillator hodoscope. The correlation coefficient and the variance of the difference of multiplicities in the two pseudorapidity regions were deterermined for s =0.3−1.8 TeV . These results have been interpreted in terms of a cluster model of particle production.

p\bar{p}

Transverse momentum spectra of charged particles produced within the pseudo-rapidity range of η= − 0.36 to + 1.0 have been measured in pp collisions at √s=0.3, 0.54, 1.0, and 1.8 TeV. The spectra are presented as a function of event charged multiplicity within the range −3.25<η<3.25. We found that the slope in the low pt region is independent of center-of-mass energy and multiplicity while the slope at the high pt region shows a strong energy and multiplicity dependence.

collisions at

Abstract In an inclusive experiment, isotopically resolved fragments, 3 ⩽ Z ⩽ 13, produced in high-energy proton-nucleus collisions, have been studied using a low mass time-of-flight, gas delta E — silicon E spectrometer and the internal gas jet at Fermi National Accelerator Laboratory. Measurement of the kinetic energy spectra from 5 MeV to 100 MeV enabled an accurate determination of fragment cross sections from both xenon and krypton targets. The observed isobaric yield is given by Y α A−τf, where τ ∼ 2.6 for both targets. The power law is the signature of the fragment formation mechanism. We treat the formation of fragments as a liquid-gas phase transition at the critical point. The critical temperature Tc can be determined from the fragment isotopic yield provided one can set an energy scale for the fragment free energy. The high energy tails of the kinetic energy spectra provide evidence that the fragments originate from a common remnant system somewhat lighter than the target which disassembles simultaneously via Coulomb repulsion into a multibody final state. Fragment Coulomb energies are about 1 10 of the tangent sphere values. The remnant is characterized by a parameter To obtained from the high energy tails of the kinetic energy distributions. To is interpreted as reflecting the mean squared momentum of a nucleon in the remnant system.

\sqrt{s}

Abstract Internal gas jet targets allow a high degree of flexibility in the design of experiments to study beam-target interactions in circular accelerators. Ultra-thin targets in the range 1–100 ng/cm 2 can be produced at essentially any available beam energy. Since the beam passes through the target approximately 10 5 times per second, the effective target thickness can be comparable to that of a typical thin foil. We have performed a number of experiments at both FNAL and the Brookhaven AGS utilizing mixed and pure gas jet targets to study proton-nucleus collisions. With thousands of hours of experience using a variety of pure and mixed gas targets, we have demonstrated that such a target facility is not only readily adapted to the physical constraints of the accelerator but also offers a wide choice of targets and detector array possibilities. In addition, a target normalization technique is presented utilizing p-p elastic scattering from the hydrogen component of the mixed gas targets.

= 0.3-TeV to 1.8-TeV

Abstract Differential cross sections for the emission of isotopically resolved fragments with A =11–28 in the interaction of 80–350 GeV/ c protons with krypton and xenon have been used to obtain the nuclear charge dispersion in the fragmentation mass region. The resulting curve has also been derived from the thermal liquid drop model. The charge dispersion is gaussian and has a mass dependent width.