Search results for "Storage"

A method of magnetic storage of ultra-cold neutrons for a precise measurement of the neutron lifetime

1999

The beta-decay lifetime of the free neutron has been determined most precisely using storage of ultra-cold neutrons (UCNs) in material bottles. The quantity measured is the storage time which is substantially smaller than due to spurious losses of UCNs at collisions with the bottle walls. The systematic uncertainty of the correction - to the true lifetime is presently the main obstacle towards higher precision in this measurement. In the alternative magnetic trapping of UCNs, storage conditions can be realized where this correction becomes vanishingly small. This paper gives a method to measure the neutron lifetime with very low systematic errors, using confinement of UCNs in vacuum by magn…

Precise Measurement of the e+e−→π+π−J/ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV

2017

The cross section for the process e(+)e(-)-> pi(+) pi(-) J/psi is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (222.0 +/- 3.1 +/- 1.4) MeV/ c(2) and a width of (44.1 +/- 4.3 +/- 2.0)MeV, while the second one has a mass of (4320.0 +/- 10.4 +/- 7.0)MeV/c(2) and a width of (101.4(- 19.7)(+25.3) +/- 10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precisi…

Precise Measurement of the e+e− → π+π−J/ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV

2020

The cross section for the process e(+)e(-)-> pi(+) pi(-) J/psi is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (222.0 +/- 3.1 +/- 1.4) MeV/ c(2) and a width of (44.1 +/- 4.3 +/- 2.0)MeV, while the second one has a mass of (4320.0 +/- 10.4 +/- 7.0)MeV/c(2) and a width of (101.4(- 19.7)(+25.3) +/- 10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precisi…

Final report on the CERN muon storage ring including the anomalous magnetic moment and the electric dipole moment of the muon, and a direct test of r…

1978

Abstract A comprehensive description of the muon storage ring and its operation is given, and the final results of the experiment are presented and discussed. The anomalous magnetic moments of positive and negative muons are found to be aμ+ = 1165911(11) × 10−9 and aμ− = 1165937(12) × 10−9 giving an average value for muons of aμ = 1165924(8.5) × 10−9. The electric dipole moments were also measured with the results Dμ+= (8.6 ± 4.5) × 10−9e · cm and Dμ− = (0.8 ± 4.3) × 10−19e · cm. Under the assumption of the CPT theorem these yield a weighted average of Dμ = (3.7 ± 3.4) × 10−19e · cm. Finally the time transformation of special relativity is shown to be valid to (0.8 ± 0.7) × 10−3 at γ ≅ 29.3…

Storage-ring experiments with exotic nuclei: from mass measurements to the future

2004

Direct mass measurements with electron-cooled ions coasting in a heavy-ion storage ring allow the mapping of large areas of the nuclear chart, well suited to explore new regions and to investigate isospin effects as well as structure changes far-off stability. In this contribution first results will be discussed, experimental masses will be compared to theoretical predictions. A study of the isospin dependence of shell strength and pairing will be made.

Radioactive beams at GSI

2001

Abstract After a brief introduction the production of relativistic beams of exotic nuclei will be discussed and some characteristic examples from the ongoing GSI nuclear structure research programme are presented, such as: nuclear reactions with exotic beams to explore nuclear skins, the structure of halo nuclei, and direct mass measurements in a storage ring. Heavy-element research will be addressed briefly. A possible next generation exotic beam facility at GSI will be outlined.

Measurements of relativistic time dilatation for positive and negative muons in a circular orbit

1977

The lifetimes of both positive and negative relativistic (γ = 29.33) muons have been measured in the CERN Muon Storage Ring with the results τ+ = 64.419 (58) µs, τ− = 64.368 (29) µs The value for positive muons is in accordance with special relativity and the measured lifetime at rest: the Einstein time dilation factor agrees with experiment with a fractional error of 2×10−3 at 95% confidence. Assuming special relativity, the mean proper lifetime for μ− is found to be τ0− = 2.1948(10) µs the most accurate value reported to date. The agreement of this value with previously measured values of τ0+ confirms CPT invariance for the weak interaction in muon decay.

First Antiprotons in an Ion Trap

1987

Measurements of the antiproton mass[2,3,4,5] are represented in Fig. 1. All of these are deduced from measurements of the energy of x-rays radiated from highly excited exotic atoms. For example, if an antiproton is captured in a Pb atom, it can make radiative transitions from its n = 20 to n = 19 state. The antiproton is still well outside the nucleus in this case, so that nuclear effects can be neglected. The measured transition energy is essentially proportional to the reduced mass of the nucleus and hence the antiproton mass can be deduced by comparing the measured values with theoretical values, corrected for QED effects. The most accurate quoted uncertainty is 5 × 10-5 and is consisten…

Emittance Growth by Synchrotron Radiation in a Double-Sided Microtron

1999

Here we present results of calculations of emittance growth caused by quantum fluctuations of synchrotron radiation (QFSR) for a 1.5 GeV double-sided microtron (DSM). We did both semi-analytical estimations, employing known Twiss parameters for the DSM orbits, and a computer simulation of these stochastic effects using the program SYTRACE. This showed that the normalized emittance growth was within reasonable limits, by a factor of about 1.5, thus permitting e.g. the installation of small aperture linacs on the DSM axes.

Test of Special Relativity in a Heavy Ion Storage Ring

2008