The OBELIX spectrometer, studying at the Low Energy Antiproton Ring (LEAR) of CERN the
N̄N annihilation, has collected annihilation data with very low momentum
p̄(≈ 50
MeV/c). The results of the ...spin-parity analysis on the
p̄p annihilation into four and five pions are briefly described.
A spin-parity analysis of a sample of p̄p→K+K−π+π−π0 annihilation events taken at rest in gaseous H2 at NTP is reported. The invariant mass spectrum of the K+K−π0 system shows the presence of the E/ι ...resonance pattern at 1.42 GeV. The analysis of this signal confirms the results obtained by the OBELIX Collaboration in previous works, namely: the existence of two pseudoscalar states at 1.413 ± 0.002 and 1.460±0.012 GeV with widths 0.051 ± 0.004 and 0.120±0.015 GeV, respectively. The p̄p system in the 3P1 wave shows also a signal corresponding to the axial vector f1(1420) decaying to K∗K̄ with mass 1.420±0.003 GeV and width 0.061±0.005 GeV. A study of the incoherent phase space background shows that its origin is mostly due to the reflection of a resonant state in the K+K−π+π− system. The isobar decomposition of this resonant state is mainly f0(1370)(ππ)S, its parameters are: JPC=0++, m=1.670±0.02 GeV and width 0.267±0.036 GeV. This signal can be probably identified with another decay mode of the f0(1710).
The Obelix experiment at CERN collected samples of antiproton annihilations at rest in different gaseous targets, such as hydrogen, deuterium and helium. We analyze a set of the Obelix data using a ...new technique for measuring, for the first time, the cascade times independent of the capture energy and of the antiproton stopping power. We report on measurements of the cascade times for hydrogen at 3.4, 5.8, 9.8 and 150 mbar and for helium at 8.2, 50 and 150 mbar pressure. An estimate of the antiproton capture energy in hydrogen is also presented.
The results of an investigation of the Pontecorvo reaction p̄d→φn with stopped antiprotons in a gaseous deuterium target at NTP are presented. A very selective dedicated trigger was used to collect a ...sample of about 8.5×106 annihilations. It is found that the annihilation rate is Y(p̄d→φn)=(3.56±0.20+0.2−0.1)×10−6. Comparison with the corresponding value for the ω-meson production demonstrates a large (a factor 40) apparent violation of the OZI rule, even larger than that found in the annihilation on a free nucleon.
SuperB Technical Design Report Collaboration, SuperB; Sapor, M; Diacono, D ...
arXiv.org,
06/2013
Paper, Journal Article
Odprti dostop
In this Technical Design Report (TDR) we describe the SuperB detector that was to be installed on the SuperB e+e- high luminosity collider. The SuperB asymmetric collider, which was to be constructed ...on the Tor Vergata campus near the INFN Frascati National Laboratory, was designed to operate both at the Upsilon(4S) center-of-mass energy with a luminosity of 10^{36} cm^{-2}s^{-1} and at the tau/charm production threshold with a luminosity of 10^{35} cm^{-2}s^{-1}. This high luminosity, producing a data sample about a factor 100 larger than present B Factories, would allow investigation of new physics effects in rare decays, CP Violation and Lepton Flavour Violation. This document details the detector design presented in the Conceptual Design Report (CDR) in 2007. The R&D and engineering studies performed to arrive at the full detector design are described, and an updated cost estimate is presented. A combination of a more realistic cost estimates and the unavailability of funds due of the global economic climate led to a formal cancelation of the project on Nov 27, 2012.
The
p
annihilation at rest in a NTP
4He-gas target has been studied by means of the Obelix spectrometer installed at the LEAR accelerator of CERN. Reactions with production of 2
π
−2
π
+, 2
π
−3
π
+, ...2
π
−2
π
+p, 2
π
−
π
+2p, 2
π
−3p (with
p
π
>80 MeV/
c and
p
p>300 MeV/
c) have been selected and single- and multinucleon annihilations identified. For the first time some known mesonic and baryonic resonances have been observed in
p
̄
4He annihilations and branching ratios are evaluated for a number of reaction channels.
Antihydrogen production and precision experiments Holzscheiter, M.H.; Bendiscioli, G.; Bertin, A. ...
Nuclear physics. Section B, Proceedings supplement,
06/1997, Letnik:
56, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The study of CPT invariance with the highest achievable precision in all particle sectors is of fundamental importance for physics. Equally important is the question of the gravitational acceleration ...of antimatter. In recent years, impressive progress has been achieved in capturing antiprotons in specially designed Penning traps, in cooling them to energies of a few milli-electron volts, and in storing them for hours in a small volume of space. Positrons have been accumulated in large numbers in similar traps, and low energy positron or positronium beams have been generated. Finally, steady progress has been made in trapping and cooling neutral atoms. Thus the ingredients to form antihydrogen at rest are at hand. Once antihydrogen atoms have been captured at low energy, spectroscopic methods can be applied to interrogate their atomic structure with extremely high precision and compare it to its normal matter counterpart, the hydrogen atom. Especially the 1S–2S transition, with a lifetime of the excited state of 122 msec and thereby a natural linewidth of 5 parts in 10
16, offers in principle the possibility to directly compare matter and antimatter properties at a level of 1 part in 10
18.
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