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In light of a 3-D Hall sensor that is being designed at the Magnet Section of the Paul Scherrer Institute (PSI), a new calibration scheme is under development. As a preparation to this, a single Hall plate is calibrated for perpendicular and in-plane field directions by rotation of the Hall plate in a calibration magnet. A piezoelectric nano rotary positioner system that fits into the 38 mm aperture of the calibration magnet will be applied. In addition, two Hall plates glued back-to-back and rotated 90^\circ around the normal axis with respect to each other are used which have the clear advantage that the planar Hall effect is nearly cancelled out. It will be shown that the full 3-D field vector of a magnetic field can be extracted by rotation of the probe(s) in the to-be-measured magnetic field. Hence, the setup can be used efficiently to measure the (inhomogeneous) magnetic field of large aperture magnets. The paper describes the calibration results and the scheme to measure the full field vector using a piezoelectric nano rotary positioner system. [ABSTRACT FROM PUBLISHER]

In this work we present the design, the construction and the measurements of the magnet for a so-called spin-rotator (Wien filter), a beam line device used to rotate the spin direction (and the associated magnetic moment) of muons in a beam used for condensed matter research at the Swiss Muon Source at the Paul Scherrer Institute. The design parameters—originating both from the properties of the preferred particle beam as well as the technological constraints for the high-voltage components generating the necessary electric field—were optimized for device compactness, cost and high beam transmission. [ABSTRACT FROM PUBLISHER]

Presents the conceptual design of the large gap Spectrometer Dipole for the Large Hadron Collider experiment. Design considerations for the yoke and the superconducting coil; Parameters of the conductor, coil and cooling system; Estimation of quench behavior.

The tolerance in the alignment of the quadrupoles in the linacs and in the undulator lines of the Swiss Free Electron Laser (SwissFEL), the next project at the Paul Scherrer Institute (PSI), will be about 1 \mum. This accuracy will be reached using beam alignment techniques. To minimize the commissioning time, it is also requested to install the quadrupoles with a precision of \pm 50\ \mum. To achieve this goal, the vibrating wire technique will be used in association with other systems to determine the position of the magnetic axis of the quadrupoles with respect to external fiducials. After a general introduction to the project and to the instrumentation principle, the novel approach developed at PSI is presented. The main innovation consists in the use of a phase lock loop (PLL) for maintaining the wire in its resonance condition. This approach simplifies the operation of the system in case the wire is moved or replaced and increases substantially the reliability of the measurement outcomes in the frame of a series test campaign. [ABSTRACT FROM PUBLISHER]

The Paul Scherrer Institute (PSI/Switzerland) is planning an X-ray free electron laser facility (SwissFEL) using novel concepts for electron emission, high gradient acceleration and effective bunch compression. Based on a normal-conducting 5.8 GeV linear accelerator, SwissFEL will cover a spectral range of 0.1-7 nm wavelength. An ultra bright electron source was first developed and commissioned in 2008 followed by the construction of a 250 MeV accelerator facility in order to validate the concepts to generate and transport high brightness beams. This facility will be used in the future as the injector for the SwissFEL linac. An amount of typically 100 magnets of 4 different types (solenoids, quadrupoles, dipoles and correctors) is required in order to preserve the high brightness and the low emittance of the femto-second electron pulses. All the magnets are designed and magnetically measured at PSI in order to ensure that the required tolerances are fulfilled. The field gradient, the multipole contents and the magnetic center position are measured with two independent systems, an automated scanner and a uniaxial Hall Probe. We review the magnet design required for the injection phase and discuss the first results of the magnetic measurements. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

At the Paul Scherrer Institute (PSI/Switzerland) a new proton gantry for cancer treatment is planned. A fast 3 dimensional scanning technique of the tumor volume is one of the medical highlights of this new gantry. The gantry will be driven by the new COMET proton cyclotron, which will deliver a cw proton beam. The energy of this beam will be adjusted by a fast degrader device. All beam line magnets should follow the energy changes of the degrader as fast as possible. Therefore the eddy current effects in the laminated bending magnets of the beam line and the gantry must be reduced by an appropriate magnet design. The paper shows measurements and numerical simulation of the dynamic behavior of the fast switched bending magnets and design schemes for eddy current reduction in the bending magnets. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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^\circ and 5^\circ. 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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

Abstract: We report the design and test of a compact, large-diameter spinflipper for ultracold neutrons based on the principle of adiabatic spinflip. A solenoid rf coil with a high diameter-to-length ratio (d/l~1.7) is surrounded by up to three short magnet coils (d/l~0.4…1.7) to provide the static gradient field. The device is optimized for low power consumption and operation in high vacuum. The magnetic field conditions necessary for full spinflipper efficiency over the full diameter were evaluated with ultracold neutrons. The measured spinflipper efficiency vs. adiabaticity correlation is in good agreement with a calculation based on an ideally linear gradient. [Copyright &y& Elsevier]

Abstract: At the Paul Scherrer Institute (PSI, Villigen, Switzerland) the existing decay muon channel has been replaced by a hybrid-type beam line consisting of two normal-conducting solenoids with rotational symmetry close to the muon production target E, followed by a conventional beam line composed of large aperture bending and quadrupole magnets with midplane symmetry. The new beam line with a design momentum of has been planned to deliver highest surface- flux onto the moderator target of the low-energy, polarized source to generate an intense LE- beam with tunable energy between 1 and 30keV for muon spin rotation applications on thin films, multi-layers and near surface regions (depths ). The main objective was the increase of solid-angle acceptance by about one order of magnitude taking into account stringent space limitations given by the geometry of the muon production target and the existing main shielding of the proton channel. Two normal-conducting solenoids as first focusing elements allow achieving this goal. With a solid-angle acceptance of the new delivers currently the surface- beam with highest flux of at a proton current of 2mA, 4-cm long graphite production target E. About 40% of the beam can be focused onto the LE- moderator target to generate LE- with a rate up to . [Copyright &y& Elsevier]

Abstract: The new protontherapy facility PROSCAN at PSI consists of a dedicated 250MeV superconducting cyclotron, new beam lines, two gantries (one new) and a new area for eye treatments. A degrader and laminated magnets in the beam line enable fast energy changes to modulate the range of the scanning pencil beam in the patient. In the design of systems and components a lot of emphasis has been put on reliability, easy maintenance and a clear separation of responsibilities. [Copyright &y& Elsevier]

Abstract: At the Paul Scherrer Institute (PSI, Villigen, Switzerland) the new high-intensity muon beam line is currently being commissioned. It replaces the previous decay muon channel. The beam line with a design momentum of has been planned to serve the needs of the low-energy, polarized positive muon source and spectrometer at PSI. A large acceptance is accomplished by installing two solenoidal magnetic lenses close to the muon production target E that is hit by the 590MeV PSI proton beam. These normal conducting solenoids limit the maximum beam momentum to . The beam is then transported by standard large aperture beam line elements to the experiment. Several slit systems and an electrostatic separator allow the control of the beam shape, momentum spread, and to reduce the background due to positrons or electrons. We present first beam measurements at the position of the moderator target, where the electrostatic separator was replaced by a straight vacuum tube. At a maximum flux of /s at a proton current of 1.9mA has been measured. About /s hit the moderator target with a size of . This will translate into a rate of up to /s being available at the spectrometer, an improvement by almost a factor of 10 with respect to the rate achieved so far. In order to cope with the increased intensity a major upgrade of the entire apparatus (hardware and software) has been undertaken parallel to this development. [Copyright &y& Elsevier]

Abstract: We have built a novel apparatus for the investigation of materials for the storage of ultracold neutrons. Neutrons are filled into a storage volume, confined at the bottom by a magnetic field, at the top by gravity and at the sides by the slit-less sample surface under investigation. For different beryllium and diamond-like carbon samples, storage times up to 200s were obtained at room temperature. The corresponding loss parameters for ultracold neutrons varied between 4.2 and per wall collision. [Copyright &y& Elsevier]

At the Paul Scherrer Institute (PSI, Villigen, Switzerland) a new high-intensity muon beam line with momentum p < 40 MeV/c is currently being commissioned. The beam line is especially designed to serve the needs of the low-energy, polarized positive muon source (LE-μ+) and LE-μ SR spectrometer at PSI. The beam line replaces the existing μ E4 muon decay channel. A large acceptance is accomplished by installing two solenoidal magnetic lenses close to the muon production target E that is hit by the 590-MeV PSI proton beam. The muons are then transported by standard large aperture quadrupoles and bending magnets to the experiment. Several slit systems and an electrostatic separator allow the control of beam shape, momentum spread, and to reduce the background due to beam positrons or electrons. Particle intensities of up to 3.5 × 108 μ+/s and 107 μ−/s are expected at 28 MeV/c beam momentum and 1.8 mA proton beam current. This will translate into a LE-μ+ rate of 7,000/s being available at the LE-μ SR spectrometer, thus achieving μ+ fluxes, that are comparable to standard μ SR facilities. [ABSTRACT FROM AUTHOR]