The Isotope and Muon Production using Advanced-Cyclotron and Target Technology Project (IMPACT) foresees the introduction of two new target stations and three new beamlines: one for radionuclide ...production and two for surface muon production. The latter forms the project, High-Intensity Muon Beams (HIMB), which plans to increase the muon rate from the current world record of 10 8 µ + /s up to 10 10 µ + /s. This work presents an overview of the future HIMB beamlines focusing on the magnet designs that have been developed to ensure increased muon rate production and transmission. Specific radiation-hard resistive coils, based on mineral insulation, are required in this case due to the proximity to the target station. A high muon capture and transmission efficiency requires solenoid-like magnets, as well as dipole magnets and crossed-field separators to select the desired particles, while suppressing unwanted background particles. The radiation-hard capture solenoid plays the most important role in the whole beamline since it must provide a high capture efficiency. Beam optics studies provided the on-axis field profile necessary for optimizing the size and shape of the capture solenoid. Therefore, the article will also elucidate on these solenoid design strategies for achieving the desired capture efficiency.
The photon beam brightness of synchrotron light facilities is increased by reducing the beam emittance. For the upgrade of the storage ring of the Swiss Light Source (SLS2), the lattice achieving a ...low emittance foresees longitudinal gradient bending (LGB) magnets producing high peak field values and quasi-hyperbolic field profiles to minimize emittance at locations of radiation. Two types of technologies are studied: a 1.4 T peak field magnet based on permanent magnet materials (PM-LGB) and a superconducting version (SC-LGB) working at almost 5 T peak, to be upgraded to 6 T in future. The baseline scenario consists in commissioning the SLS2 with 60 PM-LGB assemblies first and exchange at a later stage three PM-LGBs by superconducting ones providing a higher peak field value. Thus, the design must foresee interchangeability. In this paper, we focus on the magnetic and mechanical design aspects of the PM-LGB and on the main mechanical constraints of the SC-LGB.
Superconducting magnets cooled with cryocoolers become more and more attractive due to an increasing cooling performance and decreasing costs. This cooling mode offers new perspectives to high field ...magnets like the possibility to be installed where space is limited and the use in rotating systems. At the Paul Scherrer Institute (PSI), two projects involving superconducting magnets cooled with cryocoolers are ongoing: a compact 6 T super-bend for the upgrade of the Swiss Light Source has been designed and a concept for a new generation of proton therapy gantries for cancer treatment was proposed last year. This contribution focuses on a dedicated compact and adjustable test stand in construction at PSI aiming at the thermal, mechanical and magnetic characterization of future superconducting magnets cooled with cryocoolers under operating conditions.
We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its lifetime is ...increased by a factor of eight compared to the ground state due to the decrease in the overlap of the positron electron wave-function. The yield of delayed annihilation photons detected as a function of laser frequency is used as a new method of detecting laser-excited Ps in the 2S state. This can be considered the first step towards a new high precision measurement of the 1S–2S Ps line.
In the context of the ITER project, the winding geometry of the large-scale magnetic field coils has to be validated. A geometrical survey during manufacturing is combined with a magnetic survey of ...finished assemblies. We are developing a fluxmeter system, which is capable of sampling magnetic flux density values (or gradients thereof) at many locations distributed around the assembly. The measurement method uses low-frequency (300 mHz-1.2 Hz) ac excitation of the coil under study and acquires induced voltage values sensed by magnetic flux pickup coils. The sampling strategy leverages on the use of calibrated arrays of coils mounted on rigid supports. The supports, whose positions in space are measured with a laser tracker, carry 48 distinct coils and are placed at several locations around the perimeter of the magnet under study. Maps of induced voltage values, corresponding to time-varying magnetic flux, are recorded. In this contribution, we present experimental results obtained on the first available European double-pancake prototype (12 turns) for the toroidal field coils and compare the results with feedforward computation using magnetostatics. At 300 mHz, the global relative agreement between measured and computed signal amplitude is in the % range. It is necessary to take into account the knowledge of the actual shape of the 12-turn current filament.
The Paul Scherrer Institute (PSI/Switzerland) is developing, within the PROSCAN project, a new method of proton radiotherapy for treating cancers using a gantry based spot scanning technique for ...irradiating deep-seated tumors. Among the innovative elements are the laminated magnets in the beam lines, including the newly conceived Gantry 2, that will enable rapid energy changes (<150 ms) to modulate the range of the scanning pencil beam in three dimensions over the tumor volume. The last and multifunctional 90° bending magnet in the Gantry 2 transport system is not only the largest, but also the most challenging element. The dynamic eddy current effects during ramping were reduced with a special arrangement of laminated parts in the central pole region of the magnet. The construction of the Gantry 2 is finished and the first proton beam reached the treatment area in May 2008. The start of the patient treatment program is planned for the near future. In this paper, the 90° bending magnet construction and the results of the magnetic measurements (both static and dynamic) are presented, together with the commissioning experiences of the Gantry 2 magnet system. The results of the magnetic measurements validated the design, showing a very successful reduction of the eddy current effects so that the fast switching between two treatment energy steps (1 to 2% of the total energy) can be realized in less than 80 ms.
The SwissFEL Injector Test Facility at the Paul Scherrer Institute (PAI/Switzerland) started its operation in August 2010. This Facility represents the first stage of the 6 GeV acceleration complex ...foreseen for the SwissFEL X-Ray coherent light source planned at the PSI. The 250 MeV Injector consists of an S-Band RF photo injector followed by four S-Band acceleration structures of 4 m length each. For fine focusing corrections each accelerating structure is surrounded by four solenoids (WFS) of 0.8 m length and a maximum field of 0.1 T. Each solenoid consists of two coils in one yoke tube. To decrease the bunch length of the electron beam a magnetic bunch compressor chicane with four dipoles (AFBC2) providing a maximum magnetic field of 0.4 T for a length of 0.25 m was build. The central dipoles of the compressor chicane are sited on a movable girder to allow extensive compression studies with dipole angles between 0° and 5°. The preservation of a high brightness and a low emittance for the femto-second electron pulse impose severe tolerances in the field quality and in the magnet positioning. In this paper we review the design of two magnet types and discuss the results of field quality and magnetic axis measurements in terms of the specifications.
A radiation therapy system using carbon ions is proposed. It is based on an accelerator system of two coupled cyclotrons. The first cyclotron accelerates carbon ions (or other particles) up to 250 ...MeV/nucl. The second cyclotron is used to boost these carbon ions to 450 MeV/nucl for treatments at deep tumor sites. This separate sector cyclotron consists of six sector 3.5 T magnets with superconducting coils and four RF cavities. We report on our first results of a feasibility study of the superconducting sector magnets of this booster cyclotron. To prevent concave magnet pole edges and to achieve symmetry in the design of the magnet, the introduction of a radial gradient in the sector is proposed. A magnet geometry based on a configuration with tilted coils is presented. The field strength varies from 2.8 T to 3.5 T over 0.8 m. The viability of the magnetic design is checked with tracking simulations. The distribution of the large electromagnetic forces acting on the coil winding, evaluated using a 3D finite element analysis, is reported. The details of the superconducting coil, of the type of wires, and of the cable layout are presented. The conceptual design of the cryostat and the options for conductor protection against quench are proposed.
The PROSCAN project at the Paul Scherrer Institute (PSI/Switzerland) involves a number of innovative elements in tumor treatment. Apart from the compact superconducting dedicated proton cyclotron ...COMET, a fast energy degrader and laminated magnets in the beam lines, including the newly conceived Gantry 2, will enable rapid energy changes of the proton beam to modulate the range of the scanning pencil beam in three dimensions over the tumor volume. The last multifunctional 90deg bending magnet of the Gantry 2 transport system is not only the largest of the three gantry bending magnets, but also the most challenging element because of its dynamical eddy current effects during ramping and the reduction of these effects with a special arrangement of laminated parts in the pole of the magnet. The design of the three Gantry 2 bending magnets and measurements of the magnet field and the dynamic behavior of the two 58deg bending magnets are presented.
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