124388402
Strangelet search and particle production studies in Pb + Pb collisions at 158-A-GeV/c at CERN SPS
We searched for long-lived strange quark matter particles, so-calledstrangelets, and studied particle and antiparticle production in Pb+Pb collisions at 158 GeV/c per nucleon at zero degree production angle. We give upper limits for the production of strangelets covering a mass to charge ratio up to 120 GeV/c 2 and lifetimest lab>1.2 μs and plot invariant differential production cross sections as a function of rapidity for a variety of particles.
110306203
SVX4 User's manual
We present and describe the operation of the SVX4 chip. The SVX4 is a custom 128-channel analog to digital converter chip used by D0 and CDF in Run IIb to read out their respective silicon strip detectors. Each channel consists of an integrator (Front-End device, or FE) and a digitize/readout section (Back-End device, or BE). The input to each channel is sampled and temporarily stored in its own storage capacitor. Upon receiving a trigger signal, the relevant pipeline cell is reserved. Subsequent signals cause reserved cells to be digitized by a 128 parallel channel Wilkinson type 8-bit ADC, and then readout in byte-serial mode with optional zero suppression (sparsification). Salient features include (1) operation in either D0 mode or CDF mode (CDF mode features ''dead timeless operation'' or continued acquisition during digitization and readout) with an additional mixed mode of operation, (2) adjustable, loadable control parameters, including the integrator bandwidth and ADC polarity (only one input charge polarity will be used for Run IIb, but this feature remains for diagnostic purposes), (3) sparsified readout with nearest neighbor logic, (4) built-in charge injection with the ability for external voltage overriding for testing and calibration, and (5) a channel mask that ismore » used for either charge injection or for masking of channels with excessive DC current input during chip operation. This document is meant to familiarize the user with the functionality of the SVX4 and goes on to include specifications, pin outs, timings and electrical information. Additional information on the SVX4 can be found in Ref [1].« less
114185756
Operational experience with the D0 silicon tracker
14164208
A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization
This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration play an important role. Results from the first measurements are presented together with some considerations and outlook.
120765978
Silicon Trackers for the Super-LHC
The Large Hadron Collider (LHC) will be upgraded to the Super-LHC in 2015 to provide a tenfold increased luminosity and data rate. The inner silicon tracking detectors of the ATLAS and CMS experiments will be replaced by even more powerful devices. The technical challenges and possible solutions for the SLHC silicon trackers are described.
17193732
JET PRODUCTION AT HERA : PROGRESS AND PROBLEMS
This contribution reviews the measurements related to jet production at HERA which are available in`98. The reasons for the considerable progress achieved in the last years are summarized. The major diiculties and the limitations of these measurements as seen today are discussed. 1. What has been measured ? One of the many fascinating topics of research at the electron{proton collider HERA is the study of multi{jet events. The application of jet algorithms to characterize the properties of multi{particle hadronic nal states turned out to be a powerful and natural approach. Jet algorithms have been used intensively in the analysis of deeply inelastic scattering (DIS) and photoproduction processes. In leading{order QCD, the cross section of multi{jet events in DIS is proportional to the strong coupling constant s and the parton density functions of the proton. Several determinations of s based on jets have been performed at HERA 1, 2, 3, 4]. There are (preliminary) extractions of the proton's gluon content in NLO 5]. This approach is more direct than determinations of the gluon density from inclusive structure function measurements, and it probes the gluon density at larger momentum fractions. Events with a jet in the very forward (proton) direction of the detectors have been studied in attempts to search for signatures expected when the BFKL parton density evolution equations are valid at HERA 6]. In photoproduction, evidence for the partonic structure of the photon has been shown in studies of jet distributions 7]. In events with two reconstructed jets x , the share of the photon's momentum entering the hard scattering process, can be calculated. From the measurement of dijet cross sections diierential in x and transverse jet energy, photon parton densities could be constrained, and the p t dependence of the anomalous component of the real photon predicted by QCD could be connrmed 8]. Jet polar angle distributions for direct and resolved photons where measured to be sensitive to the spin of the corresponding gluon or quark propagators 9]. Also, LO eeective parton densities were extracted 8].
117974501
Radiative corrections to W gamma gamma production at the LHC
Radiative W production at hadron colliders is an important testing ground for the Standard Model. We consider W gamma gamma production which is sensitive to the quartic WW gamma gamma coupling. Furthermore the Standard Model amplitude for this process contains a radiation zero. We present a calculation of the NLO QCD corrections for W gamma gamma production at the LHC.
109952852
Power supply and pulsing strategies for the future linear colliders
The concept of the power delivery systems of the future linear colliders exploits the pulsed bunch structure of the beam in order to minimize the average current in the cables and the electronics and thus to reduce the material budget and heat dissipation. Although modern integrated circuit technologies are already available to design a low-power system, the concepts on how to pulse the front-end electronics and further reduce the power are not yet well understood. We propose a possible implementation of a power pulsing system based on a DC/DC converter and we choose the Analog Hadron Calorimeter as a specific example. The model features large switching currents of electronic modules in short time intervals to stimulate the inductive components along the cables and interconnections.
121398902
Design and Construction of a TPC using GEM Foils for Gas Amplification
We report on the development of a large Time Projection Chamber (TPC) for the e+e- Linear Collider (LC). Our studies concentrate on the use of Gas Electron Multiplier (GEM) foils for the gas amplification in the TPC. Charge transfer measurements are performed using a triple-GEM structure installed into a small test chamber which is irradiated with an 55Fe source. This device is operated in high magnetic fields up to 5 T. No severe drop in primary ionisation statistics is observed, but an improved suppression of ion backdrift is achieved. For optimum settings the relative ion backdrift drops to only 2 per mil. Additionally, the width of the charge cloud created by individual 55Fe photons is measured using a finely segmented strip readout behind the triple GEM structure. Charge widths between 0.2 and 0.5 mm RMS are observed. This charge broadening is reduced in high magnetic fields. Based on these experiments a prototype GEM-TPC has been constructed for further tests in the 5 T magnet and in test beams.