T. O. Meyer

Production of nucleon resonances by single diffraction dissociation at the CERN ISR

The single diffraction dissociation process pp → (pπ+π−)p has been studied at the CERN ISR at √s = 45 GeV and 0.1 < −t < 0.6 GeV2. The reaction is dominated by nucleon resonance production: pp → pN (1520) and pp → pN(1688) with cross-sections (0.25 ± 0.08) mb and (0.56 ± 0.19) mb respectively.

Double diffraction dissociation and test of pomeron factorization at the CERN ISR

Abstract We report the observation of double diffraction dissociation in the process p + p → (p π + π − ) + X at √ s of 45 GeV and momentum transfer in the − t range 0.15−0.53 GeV 2 at the CERN ISR. The relative rates for elastic, single and double dissociation reactions measured here are found to agree with the prediction of Pomeron factorization.

Neutron induced pulses in CDF forward hadron calorimeter

The use of calorimeters with very small energy sampling fractions (of the order of a few percent or less) can result in small energy fluctuations in the showers which are interpreted as large equivalent energy depositions in the calorimeter. The authors studied the nature of such fluctuations in the forward hadron calorimeter system of the collider detector at Fermilab (CDF). The results are consistent with the hypothesis that the fluctuations are due to interactions of low-energy neutrons produced in the hadronic showers of the absorbed particles with the hydrogeneous material which makes up the calorimeters structure or filling. These neutrons elastically scatter the protons in these hydrogen compounds, which heavily ionize the active media of the calorimeter, creating additional observed energy. The authors present the characteristics of the energy fluctuations and calculate an effective cross section for their production using data available from neutron source measurements and text beam and colliding beam runs. >

Background measurements during PEP-II commissioning

A variety of background detectors were installed at the interaction point of PEP-II for measurements of machine backgrounds during commissioning. Results from these detectors, machine experiments, and simulations have been used to reduce the backgrounds at PEP-II before the installation of the BaBar physics detector.