Accelerator Neutrinos

Abstract:

The NA48 experiment at the CERN SPS accelerator is making a measurement of the direct CP violation parameter epsilon'/epsilon by comparing the four rates of decay of K-S and K-L into 2(pi)(0) and pi(+)pi(-). To reconstruct the decays into 2 pi(0) the information from the almost 13500 channels of a quasi-homogeneous liquid krypton electromagnetic calorimeter is used. The readout electronics of the calorimeter has been designed to provide a dynamic range from a few MeV to about 50 GeV energy deposition per cell, and to sustain a high rate of incident particles. The system is made by cold charge preamplifiers (working at 120 degrees K), low-noise fast shapers followed by digitizer electronics at 40 MHz sampling rate that employs a gain switching technique to expand the dynamic range, where the gain can be selected for each sample individually (i.e. every 25 ns). To reduce the amount of data collected the system contains a zero suppression circuit based on halo expansion.

Abstract:

We present a measurement of the transverse momentum distribution of Z bosons produced in pp collisions at √s = 1.8 TeV from data collected by the D experiment at the Fermilab Tevatron Collider. We find good agreement between our results and current resummation calculations, and also use our data to extract nonperturbative parameters for a particular version of the resummation formalism. The resulting values are significantly more precise than obtained in previous determinations. © 2000 The American Physical Society.

Abstract:

We report a new measurement of the cross section for the production of isolated photons with transverse energies (E Tγ) above 10 GeV and pseudorapidities |η| < 2.5 in p̄ collisions at √s = 1.8 TeV. The results are based on a data sample of 107.6 pb -1 recorded during 1992-1995 with the D0 detector at the Fermilab Tevatron collider. The background, predominantly from jets which fragment to neutral mesons, was estimated using the longitudinal shower shape of photon candidates in the calorimeter. The measured cross section is in good agreement with the next-to-leading order QCD calculation for E Tγ ≳ 36 GeV. © 2000 The American Physical Society.

Abstract:

The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter presents a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behaviour is obtained. The underlying radial energy densities for the four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrization has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeters design.