Search results for "Argo"
showing 10 items of 424 documents
A compact apparatus for mass selective resonance ionization spectroscopy in a buffer gas cell
1997
Abstract An ultra-sensitive laser spectroscopic method for the investigation of transuranium nuclides has been developed based on resonance ionization in an argon buffer gas cell. This method has been combined with ion-guide extraction and mass selective direct detection of the resonantly ionized atoms. Using argon as a buffer gas, recoils of fusion reactions can be thermalized even at low pressure. The differential pumping system consists of only one roots pump and two turbo molecular pumps. The set-up has been tested with 243 Am evaporated from a filament located inside the optical gas cell. Resonance ionization is performed using a two-step excitation with an excimer-dye-laser combinatio…
A study of on-line gas cell processes at IGISOL
2010
Abstract The laser ion source at the IGISOL facility, Jyvaskyla, has been used to study the effects of the passage of a primary beam through an ion guide via the dynamic time profiles of yttrium and related molecular compounds. The accessibility of a neutral fraction for laser ionization is shown to be restricted to the nozzle region in the presence of a weak plasma. The survival of this neutral fraction cannot be explained by recombination of the buffer gas alone and perhaps indicates a suppression of the transport of ions due to a plasma-generated electric field. The concept of a competition between the processes that create and destroy the ion of interest is used to explain the different…
A simple expression for electronic stopping force of heavy ions in solids
2012
Abstract A simple expression for the electronic stopping force of heavy ions in solids is proposed based on an adaption of the Bohr’s classical stopping theory. A three-parameter model is constructed by using experimental data for helium, oxygen, argon, krypton and xenon ions in carbon, aluminum, nickel and gold targets at energies from 600 eV/u to 985 MeV/u. Total average agreements between the model and used experimental data are (−4.5 ± 47)% and (−1.6 ± 7.4)% at energies below and above the Bragg peak, respectively. The good overall agreement makes this model a good candidate for future development in stopping force prediction tools.
Proton-air cross section measurement with the ARGO-YBJ cosmic ray experiment
2009
The proton-air cross section in the energy range 1-100 TeV has been measured by the ARGO-YBJ cosmic ray experiment. The analysis is based on the flux attenuation for different atmospheric depths (i.e. zenith angles) and exploits the detector capabilities of selecting the shower development stage by means of hit multiplicity, density and lateral profile measurements at ground. The effects of shower fluctuations, the contribution of heavier primaries and the uncertainties of the hadronic interaction models, have been taken into account. The results have been used to estimate the total proton-proton cross section at center of mass energies between 70 and 500 GeV, where no accelerator data are …
Sizeable beta-strength in $^{31}$Ar (β3p) decay
2014
5 pags. ; 7 figs. ; Open Access funded by SCOAP3 - Sponsoring Consortium for Open Access Publishing in Particle Physics
Search for gamma ray bursts with the ARGO-YBJ detector in scaler mode
2009
We report on the search for Gamma Ray Bursts (GRBs) in the energy range 1-100 GeV in coincidence with the prompt emission detected by satellites using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) air shower detector. Thanks to its mountain location (Yangbajing, Tibet, P.R. China, 4300 m a.s.l.), active surface (about 6700 m**2 of Resistive Plate Chambers), and large field of view (about 2 sr, limited only by the atmospheric absorption), the ARGO-YBJ air shower detector is particularly suitable for the detection of unpredictable and short duration events such as GRBs. The search is carried out using the "single particle technique", i.e. counting all the …
Energy spectrum of cosmic protons and helium nuclei by a hybrid measurement at 4300 m a.s.l.
2014
The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured, below the so-called "knee", by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100 TeV - 700 TeV). The observed energy spectrum is compatible with a single power law with index gamma=-2.63+/-0.06.
Ion-sputtering deposition of Ca–P–O films for microscopic imaging of osteoblast cells
2007
Abstract An ion-beam sputtering technique was used to produce Ca–P–O films on borosilicate glass at room temperature from hydroxyapatite targets using nitrogen, argon and krypton beams at different acceleration voltages. The sputtering target was pressed from high purity hydroxyapatite powder or mixture of high purity hydroxyapatite powder and red phosphorus in order to optimise the film composition. The film composition, determined using time-of-flight elastic recoil detection analysis (TOF–ERDA), was found to be strongly dependent on the ion energy used for deposition. By extra doping of the target with P the correct Ca/P atomic ratio in the deposited films was reached. The films deposite…
Inner shell ionization of argon in ECRIS plasma
2018
Abstract The volumetric K α emission rate of argon emitted from the electron cyclotron resonance (ECR) heated plasmas of the JYFL (University of Jyvaskyla, Department of Physics) 14 GHz ECR ion source (ECRIS) and the 14.5 GHz Grenoble Test Source (GTS) at iThemba Laboratory for Accelerator Based Sciences have been measured to gain an understanding of the influence of the ion source tune parameters on the absolute inner shell ionization rate. It was observed that the behaviour of the ionization rate and the extracted ion beam currents react differently, depending the parametric sweep performed. The neutral gas pressure and incident microwave power was found to have the strongest influence on…
Accumulation of radiation defects and products of radiolysis in lithium orthosilicate pebbles with silicon dioxide additions under action of high abs…
2012
Abstract One of the technological problems of a fusion reactor is the change in composition and structure of ceramic breeders (Li 4 SiO 4 or Li 2 TiO 3 pebbles) during long-term operation. In this study changes in the composition and microstructure of Li 4 SiO 4 pebbles with 2.5 wt% silicon dioxide additions, fabricated by a melt-spraying process, were investigated after fast electron irradiation ( E = 5 MeV, dose rate up to 88 MGy h −1 ) with high absorbed dose from 1.3 to 10.6 GGy at high temperature (543–573 K) in air and argon atmosphere. Three types of pebbles with different diameters and grain sizes were investigated. Products of radiolysis were studied by means of FTIR and XRD. TSL …