Search results for "ION BEAMS"
showing 10 items of 44 documents
The relationship between visible light emission and species fraction of the hydrogen ion beams extracted from 2.45 GHz microwave discharge.
2015
The relationship between Balmer-α and Fulcher-band emissions with extracted H + , H + 2 , and H + 3 ions is demonstrated for a 2.45 GHz microwave discharge. Ion mass spectra and optical measurements of Balmer-α and Fulcher-band emissions have been obtained with a Wien Filter having an optical viewport on the plasma chamber axis. The beam of approximately 1 mA is analyzed for different plasma conditions simultaneously with the measurement of light emissions both with temporal resolution. The use of visible light emissions as a valuable diagnostic tool for monitoring the species fraction of the extracted beams is proposed. peerReviewed
Twin GEM-TPC prototype (HGB4) beam test at GSI and Jyväskylä : a development for the Super-FRS at FAIR
2017
The FAIR[1] facility is an international accelerator centre for research with ion and antiproton beams. It is being built at Darmstadt, Germany as an extension to the current GSI research institute. One major part of the facility will be the Super-FRS[2] separator, which will be include in phase one of the project construction. The NUSTAR experiments will benefit from the Super-FRS, which will deliver an unprecedented range of radioactive ion beams (RIB). These experiments will use beams of different energies and characteristics in three different branches; the high-energy which utilizes the RIB at relativistic energies 300-1500 MeV/u as created in the production process, the low-energy bra…
Production of zero energy radioactive beams through extraction across superfluid helium surface
2003
A radioactive Ra-223 source was immersed in superfluid helium at 1.2-1.7 K. Electric fields transported recoiled Rn-219 ions in the form of snowballs to the surface and further extracted them across the surface. The ions were focussed onto an aluminium foil and alpha particle spectra were taken with a surface barrier spectrometer. This enabled us to determine the efficiency for each process unambiguously. The pulsed second sound wave proved effective in enhancing the extraction of positive ions from the surface. Thus we offer a novel method for study of impurities in superfluid helium and propose this method for production of zero energy nuclear beams for use at radioactive ion beam facilit…
Towards commissioning the new IGISOL-4 facility
2013
Abstract The Ion Guide Isotope Separator On-Line facility at the Accelerator Laboratory of the University of Jyvaskyla is currently being re-commissioned as IGISOL-4 in a new experimental hall. Access to intense beams of protons and deuterons from a new MCC30/15 cyclotron, with continued possibility to deliver heavy-ion beams from the K = 130 MeV cyclotron, offers extensive opportunities for long periods of fundamental experimental research, developments and applications. A new layout of beam lines with a considerable increase in floor space offers new modes of operation at the facility, as well as a possibility to incorporate more complex detector setups. We present a general overview of I…
Failure analysis of normally-off GaN HEMTs under avalanche conditions
2020
Gallium nitride (GaN) high electron-mobility transistors (HEMTs) are promising devices in the power electronics field owing to their wide bandgap (WBG). However, all the potential advantages provided by their WBG require reliability improvement. In industrial applications, robustness is one of the main factors considered by circuit designers. This study focuses on the observation of the degradation behavior of the main waveforms of unclamped inductive-switching (UIS) test circuits of two different commercial GaN HEMT structures. The relevance of this study lies in the potential applications of these devices to high-voltage applications and automotive systems where they are subjected to many…
Cryogenic helium as stopping medium for high-energy ions
2008
We have investigated the survival and transport efficiency of Ra-219 ions emitted by a Ra-223 source in high-density cryogenic helium gas, with ionisation of the gas induced by a proton beam. The combined efficiency of ion survival and transport by an applied electric field was measured as a function of ionisation rate density for electric fields up to 160 V/cm and for three temperature and density combinations: 77 K, 0.18 mg/cm(3), 10 K, 0.18 mg/cm(3) and 10 K, 0.54 mg/cm(3). At low beam intensity or high electric field, an efficiency of 30%, is obtained, confirming earlier results. A sharp drop in efficiency is observed at a "threshold" ionisation rate density which increases with the squ…
A complementary laser system for ISOLDE RILIS
2011
The Resonance Ionization Laser Ion Source (RILIS) is a powerful tool for efficient and selective production of radioactive ion beams at Isotope Separator On Line (ISOL) facilities. To avoid isobaric background, highly selective stepwise resonant ionization is applied, using up to three different laser wavelengths. Due to their advantages in terms of stability and reliability, an all solid-state titanium:sapphire (Ti:Sa) system is used or is planned to be installed at the majority of on-line facilities worldwide. Such an all solid-state Ti:Sa laser system is going to be installed at the ISOLDE RILIS at CERN alongside the well-established dye laser system.
Beam cooler for low-energy radioactive ions
2001
Abstract An ion beam cooler for mass-separated radioactive ion beams has been developed and tested at the IGISOL-type mass separator facility. Technical description and characteristic properties are presented. An energy spread below 1 eV and transmission efficiency of 60% were measured.
Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR
2015
A cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RE carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance character…
Shape ofAr44: Onset of deformation in neutron-rich nuclei nearCa48
2009
The development of deformation and shape coexistence in the vicinity of doubly magic $^{48}\mathrm{Ca}$, related to the weakening of the $N=28$ shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive $^{44}\mathrm{Ar}$ beam from the SPIRAL facility at GANIL. The ${2}_{1}^{+}$ and ${2}_{2}^{+}$ states in $^{44}\mathrm{Ar}$ were excited on $^{208}\mathrm{Pb}$ and $^{109}\mathrm{Ag}$ targets at two different beam energies. $B(E2)$ values between all observed states and the spectroscopic quadrupole moment of the ${2}_{1}^{+}$ state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the $^{44}\mathrm{Ar}$ n…