F. Gasparini

Measurement of the proton electromagnetic form factor near threshold in the time-like region

The rate of the reaction pp→e+e− has been measured in liquid hydrogen for antiprotons at momentum values between 150 and 300 MeV/c. New precise values of the proton electromagnetic form factor in the time-like region have been obtained assuming |Ge|=|Gm| in the investigated region. The q2 dependence of the form factor close to threshold is found to have a steeper slope than indicated by existing calculations based on vector dominance models.

Precise determination of the electromagnetic form factor of the proton in the time-like region up to s = 4.2 GeV2

Abstract The s dependence of the proton form factor in the time-like region has been determined up to s=4.2 GeV2, assuming the validity of the |Ge| = |Gm| = |G| hypothesis. Data were taken in a dedicated experiment performed at the LEAR antiproton ring at CERN, increasing by one order of magnitude the available statistics on the proton form factor near threshold in the time-like region. Our result consist of cross section measurements of the p p → e + e − reaction for different beam momenta in the kinematical r 3.6⩽s⩽4.2 GeV2. The observed s dependence of the form factor close to threshold differs appreciably from the one suggested by previous experiments.

A large solid angle magnetic detector for precision studies of e.m. processes in low-energy p interactions

The detector presented is designed to measure the proton e.m. form factors by measuring e+e− pairs produced in pp annihilations at low energy or at rest. In this paper the apparatus is described in detail, with emphasis on how to achieve a suppression factor of about 1010 of the hadronic background.

Drift time measurements in limited streamer tubes

Abstract We have investigated the performances of drift time techniques applied to limited streamer tubes. A resolution of ∼ 150 μm in the coordinate across the wire is found and a way to solve the left-right ambiguity is presented.

A measurement of the pp→π+π− reaction for 158⩽p(p)⩽275 MeV/c

Abstract A measurement of the total cross section for the reaction p p → π+π− has been performed for seven values of the incident momentum between 158 and 275 MeV/c. The values obtained, if compared with previous results at higher momenta, agree with a 1/s dependence. The differential cross section sssumed over the whole incident momentum range has also been measured and the result of a fit by Legendre polynomials is given.

PDC: A wire chamber cathode read-out on 6-bit fast ADC

Abstract A read-out for MWPC and drift chamber is presented in which the coordinate along the sense wires is obtained by measuring the centre of gravity (CoG) of the charge induced on cathode strips or pads. The peak value of the signals coming from subsets of 8-pad cathodes are recorded by a parallel sample and hold, strobed by their own OR, and then serially digitized by one 6-bit fast ADC (FADC). The basic module of the system is peak detector and converter (PDC) built in CAMAC cards, which could be an interesting approch to the analog signal acquisition of large particle detectors. The system has been designed to equip the central detector in an experiment at the CERN LEAR facility. A prototype of a card will be described and the results of some tests will be presented.

The CMS muon detector: From the first thoughts to the final design

The project presented in this paper, the CMS muon detector, is fully described in Ref. 1. It was designed from 1991 to 19945 by a community of physicists and engineers from universities and institutes of several countries. The details of the design were fixed in 1997 with the submission of the CMS Muon Technical Design Report.4 This paper reflects the views, the memoirs and the understanding of the author, who is responsible for the choice of the subjects and for any omission or error.

High precision bidimensional readout for LST

Abstract We describe a high precision bidimensional readout for a large plastics Limited Streamer Tube (LST) system, using induced charge analog readout for the coordinate along the wires and digital readout with drift time for the other. In a test we easily obtained a resolution in the drift coordinate of about 150 μm with the possibility of solving left/right ambiguity using digital strip information.

Electron-Positron Pair Production in p\bar p Annihilation at LEAR

We report here the first results of the PS170 (APPLE) experiment [1, 2] installed on the LEAR beam, at CERN.

Precision Measurements of the Electromagnetic form Factors of the Proton in the Time-Like Region and Detailed Vector Meson Spectroscopy

The experiment has been designed for precise measurements of the proton electromagnetic form factors in the time-like region and for detailed vector meson spectroscopy in the mass range 1–1.7 GeV.