The electromagnetic structure of the lightest hadrons, proton, pion, and kaon is studied by high-precision measurements of their form factors for the highest timelike momentum transfers of ...|Q2|=s=14.2 and 17.4 GeV2. Data taken with the CLEO-c detector at sqrts=3.772 and 4.170 GeV, with integrated luminosities of 805 and 586 pb(-1), respectively, have been used to study e+ e- annihilations into π+ π-, K+ K-, and pp. The dimensional counting rule prediction that at large Q2 the quantity Q2F(Q2) for pseudoscalar mesons is nearly constant, and should vary only weakly as the strong coupling constant αS(Q2) is confirmed for both pions and kaons. However, the measurements are in strong quantitative disagreement with the predictions of the existing quantum chromodynamics-based models. For protons, it is found that the timelike form factors continue to remain nearly twice as large as the corresponding spacelike form factors measured in electron elastic scattering, in significant violation of the expectation of their equality at large Q2. Further, in contrast to pions and kaons, a significant difference is observed between the values of the corresponding quantity |Q4|G(M)(|Q2|)/μ(p) for protons at |Q2|=14.2 and 17.4 GeV2. The results suggest the constancy of |Q2|G(M)(|Q2|)/μ(p), instead, at these large |Q2|.
A calorimetric polarimeter based on inorganic LYSO scintillators is described. It has been designed for use in a storage ring to search for electric dipole moments (EDM) of charged particles such as ...the proton and deuteron. Its development and first use was on the Cooler Synchrotron (COSY) at the Forschungszentrum Jülich with 0.97 GeV/c polarized deuterons, a particle and energy suitable for an EDM search. The search requires a polarimeter with high efficiency, large analyzing power, and stable operating characteristics. With typical beam momenta of about 1 GeV/c, the scattering of protons or deuterons from a carbon target into forward angles becomes a nearly optimal choice of an analyzing reaction. The polarimeter described here consists of 52 LYSO detector modules, arranged in 4 symmetric blocks (up, down, left, right) for energy determination behind plastic scintillators for particle identification via energy loss. The commissioning results of the current setup demonstrate that the polarimeter is ready to be employed in a first direct measurement for an EDM on the deuteron, which is planned at COSY.
The data for 9.3 million Υ(2S) and 20.9 million Υ(1S) taken with the CLEO III detector have been used to study the radiative population of states identified by their decay into 26 different exclusive ...hadronic final states. In the Υ(2S) decays, an enhancement is observed at a ~5σ level at a mass of 9974.6±2.3(stat)±2.1(syst) MeV. It is attributed to η(b)(2S) and corresponds to the Υ(2S) hyperfine splitting of 48.7±2.3(stat)±2.1(syst) MeV. In the Υ(1S) decays, the identification of η(b)(1S) is confirmed at a ~3σ level with Mη(b)(1S) in agreement with its known value.
Fermilab experiment E835 has measured the cross section for the reaction p̄p→e+e− at s=11.63, 12.43, 14.40 and 18.22 GeV2. From the analysis of the 66 observed events new high-precision measurements ...of the proton magnetic form factor are obtained.
The motivation of the current R&D project is based upon the requirements of the JEDI international collaboration11http://collaborations.fz-juelich.de/ikp/jedi/. aiming to measure Electric Dipole ...Moments (EDMs) of charged particles in storage rings. One of the most important elements of such an experiment will be a specially designed polarimeter with the detection system based on a modular inorganic scintillator (LYSO crystal) calorimeter. The calorimeter modules are read out by Silicon Photo Multipliers (SiPMs). This paper describes the development of a multi-channel power supply for the polarimeter modules, providing very stable and clean bias voltages for SiPMs. In order to ensure the best possible performance of SiPMs in conjunction with the crystal-based calorimeter modules and to guarantee the required level of calorimeter stability, several quality requirements have to be met by the power supply. Additionally, it is required to provide features including remote control via the network, ramping of the output voltage, measuring and sending the information about its output voltages and currents, etc. The obtained results demonstrate that the goals for the JEDI polarimeter are met. The developed hardware will be useful in other fields of fundamental and applied research, medical diagnostic techniques and industry, where SiPMs are used.
We report results on event-by-event fluctuations of transverse momentum, Phi(p(t)), in pi(+)p and K(+)p collisions at 250 GeV/c. For the first time, their dependence on rapidity region, transverse ...momentum acceptance, multiplicity, mean transverse momentum per event, and on the correlation between transverse momentum and multiplicity are systematically presented. The results are compared with those from the PYTHIA Monte Carlo generator. The fluctuations under the same acceptance cuts as used in current heavy-ion experiments are also presented.
Experiment E835 at Fermilab Garzoglio, G.; Gollwitzer, K.; Hahn, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2004, Letnik:
519, Številka:
3
Journal Article
Recenzirano
We provide a comprehensive description of experiment E835 at Fermilab, a high-precision experimental study of charmonium bound states. The
c
̄
c
states are formed in
p
̄
p
annihilations of cooled ...antiprotons stored in the Fermilab Antiproton Accumulator using a dense internal hydrogen gas-jet target. We describe the experimental strategies adopted for detecting the tiny
c
̄
c
resonant signals in the huge non-resonant hadronic background, and for measuring resonance parameters with high precision.
PDF
