Recent DHCAL Developments

This talk reports on recent progress concerning the development of a Digital Hadron Calorimeter with Resistive Plate Chambers as active elements. After the successful testing of a Digital Hadron Calorimeter prototype, the DHCAL, in the Fermilab and CERN test beams, the DHCAL group is now tackling some of the remaining technical issues which were not addressed specifically with the prototype. The talk reports on developments related to the RPC chamber design, to improvements in the RPC rate capabilities, the high voltage distribution system, and a gas recirculation system.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS13) Tokyo, Japan, 11-15 November 201

Long-Range Correlations in Deep-Inelastic Scattering

Multiplicity correlations between the current and target regions of the Breit frame in deep-inelastic scattering processes are studied. It is shown that the correlations are sensitive to the first-order perturbative QCD effects and can be used to extract the behavior of the boson-gluon fusion rates as a function of the Bjorken variable. The behavior of the correlations is derived analytically and analyzed using a Monte Carlo simulation.Comment: 16 pages, 5 figures, preprint ANL-HEP-PR-98-46 (accepted by J. Phys. G

The Time Structure of Hadronic Showers in Calorimeters with Scintillator and with Gas Readout

Hadronic showers are characterized by a rich particle structure in the spatial as well as in the time domain. The prompt component comes from relativistic fragments that deposit energy at the ns scale, while late components are associated predominantly with neutrons in the cascade. To measure the impact of these late components, two experiments, based on gaseous and plastic active layers with steel and tungsten absorbers, were set up. The different choice for the material of the active layers produces distinct responses to neutrons, and consequently to late energy depositions. After discussing the technical aspects of these systems, we present a comparison of the signals, read out with fast digitizers with deep buffers, and provide detailed information of the time structure of hadronic showers over a long sampling window.Comment: proceeding for CALOR2014, 6 pages, 5 figure

Tests of a Novel Design of Resistive Plate Chambers

A novel design of Resistive Plate Chambers (RPCs), using only a single resistive plate, is being proposed. Based on this design, two large size prototype chambers were constructed and were tested with cosmic rays and in particle beams. The tests confirmed the viability of this new approach. In addition to showing an improved single-particle response compared to the traditional 2-plate design, the novel chambers also prove to be suitable for calorimetric applications

Status of Hard Interactions (Jets and Heavy Flavor)

We review the status of hard interactions, in particular of jet and heavy flavor production, at HERA and LEP. Emphasis is given to recent theoretical developments. Instantons, event shapes, and prompt photons are also briefly discussed.Comment: Opening plenary talk presented at DIS 2001, Bologna, April 2001. 12 pages, 9 figure

Tests of QCD at HERA: determination of the gluon density

An overview is given of the various methods available to the colliding beam experiments at HERA to determine the gluon density of the proton. The article includes a description of fits to the structure function F{sub 2}, of studies of dijet and open charm production in deep inelastic scattering, of elastic and inelastic {psi} photoproduction, and of inclusive diffractive scattering. 13 refs., 8 figs

NLO QCD predictions for internal jet shapes in DIS at HERA

The transverse momentum flow inside jets is a sensitive measure of internal jet structure. For the current jets in deep inelastic scattering this jet shape measure is determined at order alpha_s^2, i.e. with up to three partons inside a single jet. The scale dependence of jet shapes in various jet algorithms is discussed. Results agree well with recent measurements by the ZEUS Collaboration, without introducing the hadronization parameter R_sep.Comment: 10 pages, LaTeX2.09, REVTeX3.1, 9 postscript figure

Measurements of the Rate Capability of Various Resistive Plate Chambers

Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. This paper reports on measurements of the performance of three different glass RPC designs featuring a different total resistance of the resistive plates. The measurements were performed with 120 GeV protons at varying beam intensitie

Extraction of the gluon density of the proton at x

The gluon momentum density xg(x, Q2) of the proton was extracted at Q2 = 20 GeV2 for small values of x between 4 × 10-4 and 10-2 from the scaling violations of the proton structure function F2 measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on F2 at low x constrained by measurementsfrom NMC at larger x; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small x in comparison with the NMC result obtained at larger values of x. © 1995