A compact radio frequency quadrupole for ion bunching in the WITCH experiment
21 Aug 2011-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment (North-Holland)-Vol. 648, Iss: 1, pp 1-14
TL;DR: In this paper, a compact Radio Frequency Quadrupole (RFQ) ion cooler and buncher device was designed and successfully commissioned as a part of the off-line tuning system of WITCH.
Abstract: During the last several years the WITCH (Weak Interaction Trap for CHarged particles) experimental setup at ISOLDE has undergone various upgrades aiming at improvement of general performance. An essential innovation, a compact Radio Frequency Quadrupole (RFQ) ion cooler and buncher device, was designed and successfully commissioned as a part of the off-line tuning system of WITCH. The RFQ is coupled to the existing surface ionization ion source providing high intensity ion bunches (up to 10 7 ions per bunch) towards the pulsed drift tube and the Penning traps of WITCH. This achievement allows for loading and tuning of the Penning traps in the domain of space charge limits and grants off-line operation independently of the REX-ISOLDE ion source. The current upgrade allows for a more thorough and frequent testing with bunched stable ion beams of high intensities, which will be used for studying various systematic effects involved in experiments with radioactive ions.
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TL;DR: In this paper, the effective transport and cooling of singly charged ions of the isotopes 209Ra to 214Ra in a gas filled radio frequency quadrupole device is reported.
Abstract: A single Ra+ ion stored in a Paul radio frequency ion trap has excellent potential for a precision measurement of the electroweak mixing angle at low momentum transfer and as the most stable optical clock. The effective transport and cooling of singly charged ions of the isotopes 209Ra to 214Ra in a gas filled radio frequency quadrupole device is reported. The absolute frequencies of the transition 7s2S1/2–7d2D3/2 at wavelength 828 nm have been determined in 212–214Ra+ with ≤19 MHz uncertainty using laser spectroscopy on small samples of ions trapped in a linear Paul trap at the online facility Trapped Radioactive Isotopes: µicrolaboratories for fundamental Physics (TRIµP) of the Kernfysisch Versneller Instituut.
23 citations
TL;DR: In this paper, a cylindrical Penning trap with a 12-T superconducting magnet provides an increased mass and thus cluster size range, crucial to reach higher anionic charge states by means of the electron-bath method.
14 citations
TL;DR: A linear Paul trap for cooling of ion beams, the former cooler for emittance elimination radiofrequency quadrupole (RFQ) at MISTRAL/ISOLDE, has been installed and commissioned at the TRIGA-SPEC experiment located at the research reactor.
Abstract: A linear Paul trap for cooling of ion beams, the former cooler for emittance elimination radiofrequency quadrupole (RFQ) at MISTRAL/ISOLDE, has been installed and commissioned at the TRIGA-SPEC experiment located at the research reactor TRIGA Mainz. It is connected to a hot-surface-ionization ion source and a subsequent mass separator for ionization and pre-separation of neutron-rich fission products as delivered from the reactor. The capability of accumulating and bunching ion beams has been implemented to provide low-emittance ion pulses of 250 ns width containing up to 106 ions. A technical description of the upgraded RFQ as well as its characterization with stable ions is presented. Its installation allows delivery of low-emittance ion bunches to the two branches of the TRIGA-SPEC experiment, namely TRIGA-TRAP and TRIGA-LASER.
12 citations
TL;DR: In this article, the first high-statistics and high-resolution data set for the integrated recoil-ion energy spectrum following the decay of 35Ar has been collected with the WITCH retardation spectrometer located at CERN-ISOLDE.
Abstract: The first high-statistics and high-resolution data set for the integrated recoil-ion energy spectrum following the $ \beta^+$
decay of 35Ar has been collected with the WITCH retardation spectrometer located at CERN-ISOLDE. Over 25 million recoil-ion events were recorded on a large-area multichannel plate (MCP) detector with a time-stamp precision of 2ns and position resolution of 0.1mm due to the newly upgraded data acquisition based on the LPC Caen FASTER protocol. The number of recoil ions was measured for more than 15 different settings of the retardation potential, complemented by dedicated background and half-life measurements. Previously unidentified systematic effects, including an energy-dependent efficiency of the main MCP and a radiation-induced time-dependent background, have been identified and incorporated into the analysis. However, further understanding and treatment of the radiation-induced background requires additional dedicated measurements and remains the current limiting factor in extracting a beta-neutrino angular correlation coefficient for 35Ar decay using the WITCH spectrometer.
9 citations
11 Jun 2015-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the influence of space charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated, and the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.
Abstract: The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with K+39 using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.
8 citations
References
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Book•
01 Oct 1991
TL;DR: In this article, the authors present an overview of the history of electric discharge physics and its application in the field of gas discharging in the presence of longitudinal gradients of charge density.
Abstract: 1. Introduction.- 1.1 What Is the Subject of Gas Discharge Physics.- 1.2 Typical Discharges in a Constant Electric Field.- 1.3 Classification of Discharges.- 1.4 Brief History of Electric Discharge Research.- 1.5 Organization of the Book. Bibliography.- 2. Drift, Energy and Diffusion of Charged Particles in Constant Fields.- 2.1 Drift of Electrons in a Weakly Ionized Gas.- 2.2 Conduction of Ionized Gas.- 2.3 Electron Energy.- 2.4 Diffusion of Electrons.- 2.5 Ions.- 2.6 Ambipolar Diffusion.- 2.7 Electric Current in Plasma in the Presence of Longitudinal Gradients of Charge Density.- 2.8 Hydrodynamic Description of Electrons.- 3. Interaction of Electrons in an Ionized Gas with Oscillating Electric Field and Electromagnetic Waves.- 3.1 The Motion of Electrons in Oscillating Fields.- 3.2 Electron Energy.- 3.3 Basic Equations of Electrodynamics of Continuous Media.- 3.4 High-Frequency Conductivity and Dielectric Permittivity of Plasma.- 3.5 Propagation of Electromagnetic, Waves in Plasmas.- 3.6 Total Reflection of Electromagnetic Waves from Plasma and Plasma Oscillations.- 4. Production and Decay of Charged Particles.- 4.1 Electron Impact Ionization in a Constant Field.- 4.2 Other Ionization Mechanisms.- 4.3 Bulk Recombination.- 4.4 Formation and Decay of Negative Ions.- 4.5 Diffusional Loss of Charges.- 4.6 Electron Emission from Solids.- 4.7 Multiplication of Charges in a Gas via Secondary Emission.- 5. Kinetic Equation for Electrons in a Weakly Ionized Gas Placed in an Electric Field.- 5.1 Description of Electron Processes in Terms of the Velocity Distribution Function.- 5.2 Formulation of the Kinetic Equation.- 5.3 Approximation for the Angular Dependence of the Distribution Function.- 5.4 Equation of the Electron Energy Spectrum.- 5.5 Validity Criteria for the Spectrum Equation.- 5.6 Comparison of Some Conclusions Implied by the Kinetic Equation with the Result of Elementary Theory.- 5.7 Stationary Spectrum of Electrons in a Field in the Case of only Elastic Losses.- 5.8 Numerical Results for Nitrogen and Air.- 5.9 Spatially Nonuniform Fields of Arbitrary Strength.- 6. Electric Probes.- 6.1 Introduction. Electric Circuit.- 6.2 Current-Voltage Characteristic of a Single Probe.- 6.3 Theoretical Foundations of Electronic Current Diagnostics of Rarefied Plasmas.- 6.4 Procedure for Measuring the Distribution Function.- 6.5 Ionic Current to a Probe in Rarefied Plasma.- 6.6 Vacuum Diode Current and Space-Charge Layer Close to a Charged Body.- 6.7 Double Probe.- 6.8 Probe in a High-Pressure Plasma.- 7. Breakdown of Gases in Fields of Various Frequency Ranges.- 7.1 Essential Characteristics of the Phenomenon.- 7.2 Breakdown and Triggering of Self-Sustained Discharge in a Constant Homogeneous Field at Moderately Large Product of Pressure and Discharge Gap Width.- 7.3 Breakdown in Microwave Fields and Interpretation of Experimental Data Using the Elementary Theory.- 7.4 Calculation of Ionization Frequencies and Breakdown Thresholds Using the Kinetic Equation.- 7.5 Optical Breakdown.- 7.6 Methods of Exciting an RF Field in a Discharge Volume.- 7.7 Breakdown in RF and Low-Frequency Ranges.- 8. Stable Glow Discharge.- 8.1 General Structure and Observable Features.- 8.2 Current-Voltage Characteristic of Discharge Between Electrodes.- 8.3 Dark Discharge and the Role Played by Space Charge in the Formation of the Cathode Layer.- 8.4 Cathode Layer.- 8.5 Transition Region Between the Cathode Layer and the Homogeneous Positive Column.- 8.6 Positive Column.- 8.7 Heating of the Gas and Its Effect on the Current-Voltage Characteristic.- 8.8 Electronegative Gas Plasma.- 8.9 Discharge in Fast Gas Flow.- 8.10 Anode Layer.- 9. Glow Discharge Instabilities and Their Consequences.- 9.1 Causes and Consequences of Instabilities.- 9.2 Quasisteady Parameters.- 9.3 Field and Electron Temperature Perturbations in the Case of Quasisteady-State Te.- 9.4 Thermal Instability.- 9.5 Attachment Instability.- 9.6 Some Other Frequently Encountered Destabilizing Mechanisms.- 9.7 Striations.- 9.8 Contraction of the Positive Column.- 10. Arc Discharge.- 10.1 Definition and Characteristic Features of Arc Discharge.- 10.2 Arc Types.- 10.3 Arc Initiation.- 10.4 Carbon Arc in Free Air.- 10.5 Hot Cathode Arc: Processes near the Cathode.- 10.6 Cathode Spots and Vacuum Arc.- 10.7 Anode Region.- 10.8 Low-Pressure Arc with Externally Heated Cathode.- 10.9 Positive Column of High-Pressure Arc (Experimental Data).- 10.10 Plasma Temperature and V - i Characteristic of High-Pressure Arc Columns.- 10.11 The Gap Between Electron and Gas Temperatures in "Equilibrium" Plasma.- 11. Suslainment and Production of Equilibrium Plasma by Fields in Various Frequency Ranges.- 11.1 Introduction. Energy Balance in Plasma.- 11.2 Arc Column in a Constant Field.- 11.3 Inductively Coupled Radio-Frequency Discharge.- 11.4 Discharge in Microwave Fields.- 11.5 Continuous Optical Discharges.- 11.6 Plasmatrons: Generators of Dense Low-Temperature Plasma.- 12. Spark and Corona Discharges.- 12.1 General Concepts.- 12.2 Individual Electron Avalanche.- 12.3 Concept of Streamers.- 12.4 Breakdown and Streamers in Electronegative Gases (Air) in Moderately Wide Gaps with a Uniform Field.- 12.5 Spark Channel.- 12.6 Corona Discharge.- 12.7 Models of Streamer Propagation.- 12.8 Breakdown in Long Air Gaps with Strongly Nonuniform Fields (Experimental Data).- 12.9 Leader Mechanism of Breakdown of Long Gaps.- 12.10 Return Wave (Return Stroke).- 12.11 Lightning.- 12.12 Negative Stepped Leader.- 13. Capacitively Coupled Radio-Frequency Discharge.- 13.1 Drift Oscillations of Electron Gas.- 13.2 Idealized Model of the Passage of High-Frequency Current Through a Long Plane Gap at Elevated Pressures.- 13.3 V - i Characteristic of Homogeneous Positive Columns.- 13.4 Two Forms of CCRF Discharge Realization and Constant Positive Potential of Space: Experiment.- 13.5 Electrical Processes in a Nonconducting Electrode Layer and the Mechanism of Closing the Circuit Current.- 13.6 Constant Positive Potential of the Weak-Current Discharge Plasma.- 13.7 High-Current Mode.- 13.8 The Structure of a Medium-Pressure Discharge: Results of Numerical Modeling.- 13.9 Normal Current Density in Weak-Current Mode and Limits on the Existence of this Mode.- 14. Discharges in High-Power CW CO2 Lasers.- 14.1 Principles of Operation of Electric-Discharge CO2 Lasers.- 14.2 Two Methods of Heat Removal from Lasers.- 14.3 Methods of Suppressing Instabilities.- 14.4 Organization of Large-Volume Discharges Involving Gas Pumping.- References.
4,306 citations
TL;DR: In this article, the authors discuss the ways to develop techniques to isolate, contain in a trap, thermalize, and possibly refrigerate the atomic systems under observation by providing simultaneously a radiative damping mechanism, the trapping is made permanent.
Abstract: Publisher Summary This chapter discusses the ways to develop techniques to isolate, contain in a trap, thermalize, and possibly refrigerate the atomic systems under observation. The electrons move along bound orbits that are characterized by three frequencies. In ultrahigh vacuums, a beam of low-energy electrons is reflected upon itself. Temporary trapping occurs by the transformation of longitudinal kinetic energy into transverse because of e–e collisions. By providing simultaneously a radiative damping mechanism, the trapping is made permanent. Because ion–ion collisions cannot transform energy of the motion of the center of mass into the kinetic energy of the relative motion of the ions, no energy absorption from the field can take place. The ions having been formed by fast ions passing on their charge to thermal atoms may, independent of the collision parameter, be assumed to be initially at rest in good approximation. No energy input into the self-regenerating ion cloud occurs because of the collision process.
666 citations
TL;DR: The results suggest that operation of rf quadrupoles at relatively high pressure may find practical application in sampling ions from high (e.g., atmospheric) pressure ion sources.
320 citations
11 Aug 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: An ion beam cooler and buncher was developed for the manipulation of radioactive ion beams at ISOLDE/CERN as discussed by the authors, where the efficiency was found to exceed 10% in agreement with simulations.
Abstract: An ion beam cooler and buncher has been developed for the manipulation of radioactive ion beams. The gas-filled linear radiofrequency ion trap system is installed at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. Its purpose is to accumulate the 60-keV continuous ISOLDE ion beam with high efficiency and to convert it into low-energy low-emittance ion pulses. The efficiency was found to exceed 10% in agreement with simulations. A more than 10-fold reduction of the ISOLDE beam emittance can be achieved. The system has been used successfully for first on-line experiments. Its principle, setup and performance will be discussed.
268 citations
TL;DR: In this paper, the current status of precision measurements in allowed nuclear beta decay, including neutron decay, is reviewed, with emphasis on their potential to look for new physics beyond the standard electroweak model.
Abstract: The current status of precision measurements in allowed nuclear beta decay is reviewed, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. Experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. The ratio between the axial and vector couplings obtained is ${C}_{A}∕{C}_{V}=\ensuremath{-}1.269\phantom{\rule{0.2em}{0ex}}92(69)$ under standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and impact of recent developments of precision tools and of high intensity low-energy beams are also addressed.
257 citations