Search results for "IONIZATION"
showing 10 items of 1255 documents
STUDY OF SHORT-LIVED SILVER ISOTOPES WITH A LASER ION-SOURCE
1995
A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity has been applied for the study of short-lived silver isotopes at CERN/ ISOLDE. Silver atoms were ionized by two resonant excitations and final laser ionization into the continuum. Decay properties of the neutron-rich isotopes121–127Ag were studied with a neutron long-counter and aβ-detector.
Laser ion beam production at CERN-ISOLDE: New features – More possibilities
2016
Abstract This article summarizes the current specifications and the latest features of the CERN-ISOLDE resonance ionization laser ion source (RILIS). This includes a description of the optical layout and the newly designed reference system. The ionization schemes for the laser ionized beams at ISOLDE are tabulated, including six new elements. All RILIS schemes are also made publicly available in the RILIS elements on-line database. Finally, we announce a paradigm shift in RILIS operation – the combination of a machine protection and a monitoring and control system has enabled on-call operation of the laser ion source for selected beams in 2014 and has become the standard mode of operation i…
A new measurement of the 7Be(p,γ)8B cross-section with an implanted 7Be target
1999
Abstract The 7Be(p,γ)8B capture reaction is of major importance to the physics of the sun and the issues of the “solar neutrino puzzle”. We report here on a new determination of the absolute cross section of this reaction, using a novel method which overcomes some of the major experimental uncertainties of previous measurements. We utilize a 7Be target implanted into a Cu substrate and a uniformly scanned particle beam larger than the target spot, eliminating issues of target homogeneity and backscattering loss of 8B reaction products. The target was produced using a beam of 1.8·1010/s 7Be nuclei extracted at ISOLDE (CERN) from a graphite target bombarded by 1 GeV protons in a two-step reso…
Search for heavy charged long-lived particles in proton–proton collisions at s=13TeV using an ionisation measurement with the ATLAS detector
2019
This Letter presents a search for heavy charged long-lived particles produced in proton-proton collisions at root s= 13 TeV at the LHC using a data sample corresponding to an integrated luminosity ...
Helium burning of22Ne
1989
The22Ne(α, γ)26Mg and22Ne(α, n)25Mg reactions were investigated forE α(lab) from 0.71 to 2.25 MeV. Neon gas enriched to 99% in22Ne was recirculated in a differentially pumped gas target system of the extended type. Theγ-ray transitions were observed with Ge(Li) detectors and the neutrons with3He ionization chambers. A previously known resonance at ER(lab)=2.05 MeV was verified and 15 new resonances were found in the energy range covered, with the lowest at ER(lab)=0.83 MeV. Information on resonance energies, widths, strengths,γ-ray branching ratios, as well asJ π assignments, is reported. The energy range investigated corresponds to the important temperature range ofT 9 from 0.3 to 1.4 (109…
Nuclear moments and charge radii of argon isotopes between the neutron-shell closures and
2008
We report the measurement of optical isotope shifts for 40−44 Ar relative to 38 Ar from which changes in the mean square nuclear charge radii across the 1f7/2 neutron shell are deduced. In addition, the hyperfine structure of 41 Ar and 43 Ar yields the spins, magnetic dipole and electric quadrupole moments, in particular the spin I = 5/2 for 43 Ar. The investigations were carried out by fast-beam collinear laser spectroscopy using highly sensitive detection based on optical pumping and state-selective collisional ionization. Mean square charge radii are now known from 32 Ar to 46 Ar, covering sd-shell as well as f7/2-shell nuclei. They are discussed in the framework of spherical SGII Skyrme…
Measurement of inclusive ρ0, f0(980), f2(1270), K and f′2(1525) production in Z0 decays
1999
DELPHI results are presented on the inclusive production of the neutral mesons ρ0, f0(980), f2(1270), KView the MathML source and f′2(1525) in hadronic Z0 decays. They are based on about 2 million multihadronic events collected in 1994 and 1995, using the particle identification capabilities of the DELPHI Ring Imaging Cherenkov detectors and measured ionization losses in the Time Projection Chamber. The total production rates per hadronic Z0 decay have been determined to be: 1.19±0.10 for ρ0; 0.164±0.021 for f0(980); 0.214±0.038 for f2(1270); 0.073±0.023 for KView the MathML source; and 0.012±0.006 for f′2(1525). The total production rates for all mesons and differential cross-sections for …
Optical measurement of the longitudinal ion distribution of bunched ion beams in the ESR
2013
Abstract An optical technique to study the longitudinal distribution of ions in a bunched ion beam circulating in a storage ring is presented. It is based on the arrival-time analysis of photons emitted after collisional excitation of residual gas molecules. The beam-induced fluorescence was investigated in the ultraviolet regime with a channeltron and in the visible region using a photomultiplier tube. Both were applied to investigate the longitudinal shape of bunched and electron-cooled 209Bi80+ ion beams at about 400 MeV/u in the experimental storage ring (ESR) at GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt, Germany. Bunch lengths were determined with an uncertainty of abo…
New experimental method for investigation of the nucleon polarizabilities
2010
Abstract At the continuous wave (cw) Superconducting Darmstadt Electron Linear Accelerator S-DALINAC, a new method has been developed for the determination of the electric ( α ¯ ) and magnetic ( β ¯ ) polarizabilities of the proton and the deuteron. For that purpose the energy and angular dependence of the differential cross-section for elastic γ p and γ d scattering of bremsstrahlung photons in the energy range between 20 and 100 MeV is measured by detecting the recoiling proton (deuteron) in coincidence with the scattered bremsstrahlung photon. α ¯ and β ¯ are then found by means of a best fit to a theoretical description of the scattering cross-section with these quantities as open param…
A large-area transition radiation detector
1990
Abstract The construction and the operation of a large-area transition radiation detector (TRD) for the NA31 experiment at CERN are described. The TRD incorporates several novel features for stabilizing the detector response. The density of the gas mixture (xenon+helium+methane) in the detection chambers is matched to the carbon dioxide gas in the surrounding radiators by tuning the helium concentration to avoid a hydrostatic pressure difference, which would deform the chamber walls. The chamber pressure is continuously regulated by computer control to maintain it to within 1 μbar of the radiator pressure. The gas gain of each of the four chambers is regulated to better than 0.2% by changin…