Abstract In the framework of the Future Circular Collider Study a new septum magnet concept, nicknamed ‘SuShi’ has been developed, and a prototype was built at Wigner Research Center for Physics, and ...tested at the FREIA facility of Uppsala University in April 2023. The concept uses a canted cosine theta (CCT)-like superconducting magnet and a passive superconducting shield to create a zero-field and high-field region within its aperture. SuShi is the first CCT magnet with both of its winding layers simultaneously impregnated with wax. This paper describes the first powering test of the empty magnet at 4.2 K, without the shield being inserted in its aperture. The performance of the magnet, including the observation of quench-back, estimation of hot-spot temperatures and the fraction of energy dissipated in the magnet are presented, and most interestingly the absence of any quench during the entire testing period is reported. Sushi reached its nominal +5% peak field of 3.64 T at 450 A, which corresponds to 80% of the calculated short sample limit along the load line, without training.
In the framework of the future circular collider study, a new septum magnet concept ("SuShi") has been developed, and a prototype was built at Wigner RCP, and tested at the FREIA facility of Uppsala ...University. The concept uses a canted cosine theta (CCT)-like superconducting magnet and a passive superconducting shield to create a zero-field and high-field region within its aperture. SuShi is the first CCT magnet with both of its winding layers simultaneously impregnated with wax. Details of the construction will be presented, with special emphasis on the wax impregnation procedure which deals with the <inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula>15% contraction of wax upon solidification. The empty magnet (no shield in its aperture) was powered without training to 450 A with a peak field of 3.64 T, corresponding to 80% of the short sample limit of the conductor along the load line. No quench or other anomaly was observed during the entire testing period. A clear onset of quench-back was observed above about 200 A.
The Future Circular Collider proton-proton ring would require a high-field septum magnet with a blade as thin as possible for the extraction of the 50 TeV proton beam from the ring. One of the two ...baseline concepts in the conceptual design report is the "superconducting shield" (nicknamed as SuShi) septum, utilizing a zero field cooled, passive superconducting shield in order to create a zero-field channel for the circulating beam inside the bore of a 3 Tesla canted cosine theta (CCT) type superconducting magnet. Besides the overview of the magnet design, progress in the construction of the prototype is presented.
A new extraction technique has been studied at the CERN Proton Synchrotron with a view of using it for the fixed-target physics programme at the Super Proton Synchrotron. The extraction scheme is ...based on advanced concepts of non-linear beam dynamics: prior to extraction a particle beam is split into several beamlets in a transverse plane by crossing a stable resonance, which allows extracting the beamlets over multiple turns. The principle of the extraction, the detail of its implementation, and the progress of the beam commissioning over the years are discussed here. More importantly, the results obtained during the first period of successful use for the physics programme are presented, focusing on the performance analysis of the novel extraction.
Abstract
Recent years have seen an increased interest in the use of helium for radiation therapy of cancer. Helium ions can be more precisely delivered to the tumour than protons or carbon ions, ...presently the only beams licensed for treatment, with a biological effectiveness between the two. The accelerator required for helium is considerably smaller than a standard carbon ion synchrotron. To exploit the potential of helium therapy and of other emerging particle therapy techniques, in the framework of the Next Ion Medical Machine Study (NIMMS) at CERN, the design of a compact synchrotron optimised for acceleration of proton and helium beams has been investigated. The synchrotron is based on a new magnet design, profits from a novel injector linac, and can provide both slow and fast extraction for conventional and FLASH therapy. Production of mini-beams, and operation with multiple ions for imaging and treatment are also considered. This accelerator is intended to become the main element of a facility devoted to a parallel programme of cancer research and treatment with proton and helium beams, to both cure patients and contribute to the assessment of helium beams as a new tool to fight cancer.
In the framework of the Physics Beyond Colliders study (PBC) at CERN, considerable efforts are being made to reduce the beam loss and remnant activation of the slow extraction equipment in the SPS ...LSS2 region. Simulations have demonstrated that changing the material of the septum anode, presently consisting of an array of WRe wires, for a low-Z alternative could reduce the overall activation of the extraction region in the order of 30%. A laboratory test set-up was built, allowing the high voltage (HV) testing of anodes using wires made of different materials. This paper outlines the operational requirements for the anode materials and presents the experimental results of HV tests with low-Z alternatives, such as carbon nanotube (CNT) wires and Titanium alloy wires.
Following a successful commissioning period, the multiturn extraction (MTE) at the CERN Proton Synchrotron (PS) has been applied for the fixed-target physics programme at the Super Proton Synchrotron ...(SPS) since September 2015. This exceptional extraction technique was proposed to replace the long-serving continuous transfer (CT) extraction, which has the drawback of inducing high activation in the ring. MTE exploits the principles of nonlinear beam dynamics to perform loss-free beam splitting in the horizontal phase space. Over multiple turns, the resulting beamlets are then transferred to the downstream accelerator. The operational deployment of MTE was rendered possible by the full understanding and mitigation of different hardware limitations and by redesigning the extraction trajectories and nonlinear optics, which was required due to the installation of a dummy septum to reduce the activation of the magnetic extraction septum. This paper focuses on these key features including the use of the transverse damper and the septum shadowing, which allowed a transition from the MTE study to a mature operational extraction scheme.
In the framework of the LHC Injector Upgrade (LIU) project, the high field electrostatic septa (so-called ZS) have been upgraded to comply with the new requirements. Prior to their installation in ...the SPS accelerator in 2020, the septa were tested to verify their final performance. This report summarises the results of these final acceptance tests, covering the vacuum acceptance test, the HV conditioning, the final beam impedance measurements together with the ZS interconnects and validation of the upgraded ion trap system.
In the framework of the Physics Beyond Colliders (PBC) study at CERN, the Electric Dipole Moment (EDM) working group is investigating the feasibility of building an approximately 500 m circumference ...storage ring to precisely measure the permanent electric dipole moment of the proton. Protons are stored in an EDM ring at the so-called 'magic' energy of 233 MeV using only electric field elements in order to ensure that spin and momentum vectors precess horizontally at the same rate. For a proton with longitudinal spin, any EDM manifests itself as a measurable vertical spin precession. This article describes the challenges related to the electrostatic accelerator optics elements composing the storage ring. The demanding vacuum requirements, combined with the large scale and absolute absence of perturbing (residual) magnetic fields are to be taken into account for the design of the electrostatic bends, quadrupoles, as well as injection elements. The feasibility of reaching the required field tolerances is discussed. Finally, a strategy is explored to allow the conditioning of the large number of high electric field devices to assure an extremely low spark rate during operation of the storage ring.
In the framework of the LIU project, new septa magnets have been designed between CERN's PS booster (PSB) extraction and PS injection. The upgraded devices are to deal with the increased beam energy ...from 1.4 to 2 GeV at extraction of the PSB. The direct drive recombination septa in the PSB transfer line to the PS and the eddy current PS injection septum together with a bumper at injection have been investigated using finite-element software. For the recombination magnets, an increase in magnet length is sufficient to obtain the required deflection; however, for the PS injection elements, a more novel solution is necessary to also achieve increased robustness to extend the expected lifetime of the pulsed device. The injection septum will share the same vacuum vessel with an injection bumper, and both magnets will be located adjacent to each other. The new PS injection magnet will be the first septum operated at CERN based on eddy current technology. The magnetic modeling of the devices, the comparison of the performance of the present 1.4-GeV devices with the predictions for the upgraded 2-GeV devices, and the solutions retained to achieve the field requirements are described in this paper.
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