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Abstract The Isochronous Mass Spectrometry (IMS) based on storage rings is a powerful technique for mass measurement of short-lived exotic nuclei. The transition energy γ t of the storage ring is a vital parameter of the IMS technique. It is difficult to measure the γ t and its relation to momentum spread or circulating length, especially to monitor the variation of γ t during experiments. An experimental investigation on the γ t has been performed for the IMS experiment at the Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSRe). With the velocity measured by two time-of-flight (TOF) detectors, the γ t as a function of orbital length can be determined. The influences of higher order magnetic field components on the γ t function were inferred for isochronous correction. This paper introduces and investigates the influence of dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields on the γ t function. With the quadrupole magnets and sextupole magnets corrections, a mass resolution of 171332 (FWHM) and σ (T) ∕ T = 1. 34 × 1 0 − 6 were reached, which shall be compared with 31319 (FWHM) and σ (T) ∕ T = 7. 35 × 1 0 − 6 obtained without correction. [ABSTRACT FROM AUTHOR]

In this paper the closed orbit correction of the Heavy Ion Medical Machine (HIMM) synchrotron is described. Results of simulations and measurements are presented. Consistently with simulations, it is possible to correct the maximum closed orbit distortion of the HIMM synchrotron down to 2.4mm in the horizontal direction and 0.7mm in the vertical one. The errors of dipole magnets, especially the longitudinal alignment errors (Δ s), have large impact on the horizontal correction results. A Singular Value Decomposition (SVD) algorithm is adopted for computing the correction. The residual orbits and the effects of reducing the number of singular values are analytically expressed and simulated. In addition, the influences of BPM reading errors as well as corrector setting errors are analyzed. For further optimization, the method to estimate the dipole errors is studied. In the commissioning, the maximum closed orbits at BPMs can also be well corrected to within 1mm through SVD algorithm. [ABSTRACT FROM AUTHOR]

Heavy ion beam lost on the accelerator vacuum wall will release quantity of gas molecules and make the vacuum system deteriorate seriously. This phenomenon is called dynamic vacuum effect, observed at CERN, GSI and BNL, leading to the decrease of beam lifetime when increasing beam intensity. Heavy ion-induced gas desorption, which results in dynamic vacuum effect, becomes one of the most important problems for future accelerators proposed to operate with intermediate charge state beams. In order to investigate the mechanism of this effect and find the solution method for the IMP future project High Intensity heavy-ion Accelerator Facility (HIAF), which is designed to extract 1 × 1 0 11 uranium particles with intermediate charge state per cycle, two dedicated experiment setups have been installed at the beam line of the CSR and the 320 kV HV platform respectively. Recently, experiment was performed at the 320 kV HV platform to study effective gas desorption with oxygen-free copper target irradiated with continuous Xe 10 + beam and O + beam in low energy regime. Gas desorption yield in this energy regime was calculated and the link between gas desorption and electronic energy loss in Cu target was proved. These results will be used to support simulations about dynamic vacuum effect and optimizations about efficiency of collimators to be installed in the HIAF main synchrotron BRing, and will also provide guidance for future gas desorption measurements in high energy regime. [ABSTRACT FROM AUTHOR]

Abstract The longitudinal dynamics of electron-cooled and radio-frequency (RF)-bunched 12 C 6 + and 16 O 8 + ion beams have been investigated at a heavy-ion experimental cooler storage ring CSRe. An rf-buncher was employed to longitudinally modulate the ion beams. A new resonant Schottky pick-up was applied to monitor the intensities and longitudinal dynamics of stored and electron-cooled ion beams. Using electron-cooling, the separated Schottky noise signals of the 12 C 6 + and 16 O 8 + ions were clearly observed in the Schottky spectrum. The storage times and the particle numbers of both ion beams were measured by Schottky noise, which demonstrated the ability to perform Schottky mass spectrometry measurements and also the measurement of highly charged ions at the CSRe. In addition, an enhancement of the Schottky noise signals was observed for rf-bunched ion beams, which could be used to diagnose the intensity ion beams at storage rings. Finally, a broadly longitudinal manipulation of the ion beams by scanning the bunching frequency was realized. The investigation of electron–ion recombination experiment at ultra-low collision energies by scanning the bunching frequency of the ion beams at the storage ring CSRe is proposed. Highlights • The individual lifetimes and numbers of the 12 C 6 + and 16 O 8 + ions were measured. • An enhancement of the Schottky noise signals was observed for rf-bunched ion beams. • A broadly longitudinal manipulation of the ion beams was realized. [ABSTRACT FROM AUTHOR]

Dielectronic recombination (DR) experiments of highly charged ions at the storage rings have been developed as a precision spectroscopic tool to investigate the atomic structure as well as nuclear properties of stable and unstable nuclei. The DR experiment on lithium-like argon ions was successfully performed at main Cooler Storage Ring (CSRm) at Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex. The DR experiments on heavy highly charged ions and even radioactive ions are currently under preparation at the experimental Cooler Storage Ring (CSRe) at HIRFL. The current status of DR experiments at the CSRm and the preparation of the DR experiments at the CSRe are presented. In addition, an overview of DR experiments by employing an electron cooler and a separated ultra-cold electron target at the upcoming High Intensity heavy ion Accelerator Facility (HIAF) will be given. [ABSTRACT FROM AUTHOR]

A new project, High Intensity heavy ion Accelerator Facility (HIAF), is currently being under design and construction in China. HIAF will provide beams of stable and unstable heavy ions with high energies, high intensities and high quality. An overview of new opportunities for atomic physics using highly charged ions and radioactive heavy ions at HIAF is given. [ABSTRACT FROM AUTHOR]

We report on an experiment that was conducted in preparation of laser cooling experiments at the heavy-ion storage ring CSRe. The lifetimes of ion beams made up of 12 C 3+ and 16 O 4+ ions stored at an energy of 122 MeV/u in the CSRe were determined by two independent methods, firstly via a DC current transformer (DCCT) and secondly via a Schottky resonator. Using electron-cooling, the signals of the 12 C 3+ and 16 O 4+ ions could be separated and clearly observed in the Schottky spectrum. The obtained individual lifetimes of the 12 C 3+ and 16 O 4+ components were 23.6 s and 17.8 s, respectively. The proportion of 12 C 3+ ions in the stored ion beam was measured to be more than 70% at the beginning of the injection and increasing as a function of time. In addition to these measurements, the operation and remote control of a pulsed laser system placed directly next to the storage ring was tested in a setup similar to the one envisaged for future laser experiments. [ABSTRACT FROM AUTHOR]

At the heavy ion storage ring HIRFL-CSRe an electron cooler is operated to improve the beam conditions for experiments. The properties of cooled beams have been studied. The longitudinal beam dynamics during the cooling process was measured by a resonant Schottky detector. The dependencies of the parameters electron beam density and profile on cooling times were investigated. The friction force was measured directly with the aid of the high voltage system of the cooler and with the application of the beam bunching system as well. An experiment with bunched cold beam showed a dependence of the bunch length on the beam density. [ABSTRACT FROM AUTHOR]