Abstract: A calibration method for an MPI (=magnetic particle imaging) apparatus for conducting an MPI experiment, wherein the calibration method comprises m calibration MPI measurements with a calibration test piece and uses these measurements to create an image reconstruction matrix with which the signal contributions of N voxels within an investigation volume of the MPI apparatus are determined, wherein compressed sensing steps are applied in the calibration method with a transformation matrix that sparsifies the image construction matrix, and wherein only a number M<N of calibration MPI measurements for M voxels are carried out, from which the image reconstruction matrix is created and stored. This specifies an efficient method for determination of the system matrix for the MPI imaging method, which does not require much time to determine an MPI system function and nevertheless achieves a high degree of precision.

Abstract: An NMR apparatus includes a superconducting magnet assembly, a cryostat having a vacuum vessel, a refrigeration stage that can be operated at a temperature of <100 K, and a magnet coil system that comprises a cold bore into which a room temperature access of the cryostat engages. The NMR apparatus also includes an NMR probe with probe components cooled to an operating temperature of <100 K. The probe components are arranged between the cold bore and the room temperature access into the cold bore, radially inside the cold bore but outside the room temperature access. The vacuum vessel includes an opening that can be closed by a lock valve. A lock chamber is directly connected to the opening, such that the cooled probe components can be installed and/or removed through the opening and lock valve without breaking the vacuum in the vacuum vessel of the cryostat.

Abstract: A method for determining the spatial distribution of magnetic resonance signals from at least one of N subvolumes predefines a reception encoding scheme and determines unique spatial encoding for at least one of the subvolumes but not for the entire volume under examination (UV). A transmission encoding scheme is also defined, wherein encoding is effected via the amplitude and/or phase of the transverse magnetization. The temporal amplitude and phase profile of the RF pulses is then calculated and each reception encoding step is carried out I times with variations according to the I transmission encoding steps in the transmission encoding scheme. The method makes it possible to largely restrict the spatially resolving MR signal encoding and image reconstruction to subvolumes of the object under examination without the achievable image quality sensitively depending on imperfections in the MR apparatus.

Abstract: A probehead of an NMR-MAS apparatus with a rotation axis (RA), which lies in an xz-plane, titled by an angle ?>0 relative to a z-axis. The angle ? is adjusted by tilting around a tilt axis (DA) parallel to the y-axis relative to a target angle ?target. An angle measurement apparatus (9) has a first sensor element (7), which, together with a second sensor element (8) generates sensor signals dependent on the amplitude B0 of the static magnetic field and the vectorial orientation between the magnetic field B0 and a sensitivity vector. Two sensitivity vectors have an angle 5°<?i<175° to the z-axis and an angle ?>10° to each other. The angle between the rotation axis and the z-axis can be measured precisely and reliably over a large range, providing a feedback signal for regulated adjustment or tracking of the angle ?.

Abstract: Device for alternating examination of a measurement object (103) by means of MPI and MRI within a magnetic system is characterized in that the magnetic system has a specified magnetic field profile, which is not temporally variable during the alternating examination, and both magnetic field generating elements (101,102; 201,202; 801a,801b,811,812) generate a magnetic field portion, in the first examination region (104) and in the second examination region (105), which is essential for the MRI operation and for the MPI operation, and in that there is a transport apparatus (106) by means of which the measurement object can be moved out of the first examination region and into the second examination region and/or vice versa. The total space requirement for both modalities is thus reduced and the complexity of an integrally designed hybrid system is minimized.

Abstract: A superconducting magnet assembly includes a cryostat, a vacuum vessel and a refrigeration stage. An NMR probe using the assembly includes comprises cooled probe components, a two-stage cryocooler, and a counter flow heat exchanger. A cooling circuit guides coolant from one outlet of the counter flow heat exchanger back to an inlet of the counter flow heat exchanger via the second cooling stage, a cooled probe component, and a heat exchanger in the cryostat or a heat exchanger in a helium suspension tube. Both the intake temperature of the coolant flowing into the heat exchanger in the cryostat or in the suspension tube and the return flow temperature of the emerging coolant are at least 5 K lower than the operating temperature of the first cooling stage. Excess cooling capacity of the cryocooler reduces the evaporation rate of liquid helium or cools a superconducting magnet in a cryogen-free cryostat.

Abstract: An apparatus to detect gamma rays, comprising a scintillator, a position sensitive photo sensor and a scintillation-light-incidence-angle-constraining, SLIAC, element, the scintillator has faces and the position sensitive photo sensor detects scintillation photons exiting a scintillation photons transparent face of the scintillator, and a portion of a scintillator face is covered with an absorbing layer, which absorbs scintillation photons created by scintillation events due to the interaction of incoming gamma rays with the scintillator, and the SLIAC element is optically coupled between a scintillation photons transparent face of the scintillator and the position sensitive photo sensor and the SLIAC element guides the scintillation photons exiting the scintillator towards the position sensitive photo sensor, and the SLIAC element restricts the maximum allowed half light acceptance angle for the scintillation light hitting the position sensitive photo sensor to less than 45°.

Abstract: A transport device for transporting an NMR sample to the probe head (16) of an NMR spectrometer by means of a transport system (12) is characterized in that the transport device comprises a shuttle (15) adapted for use with a transport system. The transport system is structured to transport an HR-NMR sample spinner or an NMR MAS rotor (5). The shuttle includes a locking device for the NMR MAS rotor, the locking device being formed such that the NMR MAS rotor is released by unlocking the locking device and can be transferred to and received by the NMR MAS probe head. It is therefore possible to rapidly change from NMR spectroscopy of liquids to NMR spectroscopy of solids, and vice versa, simply by exchanging the probe head, without converting the transport system.

Abstract: A method for generating a desired temporal profile of the magnetization state in an object under examination (O) during an experiment involving magnetic resonance is characterized in that at least one spatially dependent change in the magnetization state inside the object under examination (O) is predefined and spatially selective radio-frequency pulses, which allow a simultaneous and independent change in the magnetization state at locations with different stipulations, are irradiated in order to implement the predefined spatially dependent change in the magnetization state. The method permits establishment of the same desired temporal profile of the magnetization state for different regions of the object under examination despite different given experimental parameters or deliberate generation of different desired profiles of the magnetization state at different locations.

Abstract: A method for determining the position of at least one ferromagnetic particle (30) in a liquid matrix (31) with an MRI system (50). An MRI measurement sequence (MS1, MS2) is applied (20) to a measurement volume (52) in which the particle is situated. The measurement sequence includes a plurality of individual measurements (E1, E2), during each of which there is a spatially encoding gradient switching operation, including an excitation pulse (1) and signal recording (2), via the MRI system. The measurement sequence has a multiplicity of measurement blocks (MB1, MB2), which each include one or more individual measurements and, in a pause of the spatial encoding, an intermediate gradient (ZW) switched by the MRI system. The intermediate gradients are dimensioned such that, averaged over time, the particle is kept substantially in the same position (M1, M2) over each measurement block.

Abstract: A gradient coil system has a cylindrical section in a central region, which contains no conductor elements and has a maximum outer radius that is larger than a minimum inner radius of conductor elements of a main gradient coil. An outer radius of this cylindrical section is only insubstantially smaller or equal in size to a minimum inner radius of a shielding coil in this axial range. The free space in the center of the gradient coil system is used to insert a passive RF shield, whose radius in a central region becomes larger over a certain length than its radius in outer regions. The RF shield is constructed from at least three partial sections, which are electrically interconnected. The actively shielded gradient coil system maximizes the volume of the RF region without loss of gradient coil system performance.

Abstract: A method for homogenizing the static magnetic field with a distribution B0(r) in the active volume of a magnetic resonance apparatus having a number N of shim coils defines a target field distribution B0T(r) using a filter method in which a norm of the shim currents is influenced by means of filter factors. An optimization procedure works in a parameter space having M control parameters, wherein 2?M<N. One of the control parameters is used as a weighting parameter for modification of a spatial weighting function and another control parameter is used to control the filter factors. Using this method the hardware limitations can be taken into account when determining the target field distribution, without a significant increase in the computational effort to determine the target field distribution during optimization.

Abstract: A method for indicating the level of a liquefied gas in a cryogenic tank having a resistance temperature detector (1). The controller applies a heating pulse to the detector and performs a single resistance measurement after the heating pulse. The overheating of the sensor and the time interval for the measurement are found in a separate set of test experiment. As a result, for temperature sensors with negative temperature coefficient, the resistance of the sensor in gas is below some unique characteristic value, which can be used like a threshold criterion to distinguish between the liquid and the gas in a wide temperature range. For sensors with positive temperature coefficient, the resistance of the sensor in gas is larger than some unique characteristic value, which can be used like a threshold criterion to distinguish between the liquid and the gas in a wide temperature range.

Abstract: Apparatus and method for performing depth sectioned fluorescence imaging of a turbid sample including a fluorescent turbid medium, uses an apparatus for quantitative modulated fluorescence imaging, the apparatus including projection optics with a first optical axis, to expose the turbid sample to a periodic pattern of excitation radiation to provide depth-resolved discrimination of fluorescent structures within the turbid medium; an image capture module, including a second optical axis and a detection beam path, to receive a data image from the sample; and a signal processor to transform the data image from the sample, spatially filter the transformed data image from the sample, and reconstruct the filtered, transformed data image from the sample.

Abstract: An NMR MAS probe head (1) has an MAS stator (7) with a base bearing (8) and a front bearing (75) for receiving a substance to be measured at a measurement position within an MAS rotor. The front bearing has an opening for inserting the MAS rotor into the space between the base bearing and the front bearing. The opening can be closed by a closing device that, in a loading state, opens and, in a measuring state, closes the opening by means of a movement that is transverse with respect to an axis (a) through the centers of the base bearing and the opening of the front bearing of the MAS stator. This enables automated loading and unloading of the MAS rotor in the space between the base bearing and the front bearing inside the MAS stator in a simple way.

Abstract: An NMR apparatus includes a superconducting magnet coil system configured to generate a homogeneous magnetic field, and a helium (He) tank having an inner tube mechanically rigidly connected to the He tank and in which the magnet coil system is positioned. The He tank is configured to contain liquid helium to cool the magnet coils. A radiation shield has a radiation shield inner tube encompassing the He tank and spaced from the He inner tube to create a space between the He inner tube and the radiation shield inner tube to reduce an evaporation rate of the liquid helium. The NMR apparatus additionally includes a field shaping device with a magnetic material arranged in the space, in order to shim the homogeneous magnetic field. The field shaping device is fixed in the space so as to be in rigid mechanical contact with the He tank but without contacting the radiation shield.

Abstract: A DNP apparatus includes a cryostat (7) having an opening (8) and a loading path for a sample (1), the loading path extending from the opening to a sample receptacle (29), with a cryomagnet and a microwave source (2) as well as a configuration for supplying microwave radiation from the microwave source to the sample, which comprises a microwave path extending directly to the sample. The microwave path extends spatially separately from the loading path and the configuration for supplying microwave radiation has at least one microwave feed-through passing through one or more walls of the cryostat. The microwave path is incident on the sample from a direction opposite to the loading path or from a sideward direction at right angles to or at an inclination with respect to the axis of the loading path. This leads to simple and efficient polarization of the electron spins in the sample.

Abstract: An NMR probe head (3) has a coil system (9) and a radial centering mechanism for a sample vial (4) having two centering devices spaced axially from each other to center the sample vial in the radial direction only. The first centering device (5) is disposed above the receiver coil system and at least one further centering device (6) is disposed axially above the coil system with an axial spacing (d) above the first centering device. The first and second centering devices restrict the radial scope for movement of the sample vial to such an extent that the sample vial cannot touch an endangered space (7) during the entire duration of transport of the sample vial to its measuring position, thereby precluding damage to the probe head components in the endangered space by the sample vial.

Abstract: A method for charging a magnet arrangement having a superconducting tape conductor with a first transition temperature in a cryostat device. The magnet arrangement is temperature-controlled to a first pre-operating temperature between the first transition temperature and the operating temperature, a first pre-operating current is excited, the magnet arrangement is cooled to operating temperature and a first operating current is excited. The magnet arrangement has a second magnet winding composed of a second superconductor material with a second transition temperature above the operating temperature and at least 15 K below the first transition temperature, wherein a second operating current in the second magnet winding is excited at the latest after cooling of the magnet arrangement to the operating temperature, and with the second operating current the second magnet winding generates a second operating magnetic field in the volume of the first magnet winding.

Abstract: An NMR apparatus includes a superconducting magnet coil system configured to generate a homogeneous magnetic field, and a helium (He) tank having an inner tube mechanically rigidly connected to the He tank and in which the magnet coil system is positioned. The He tank is configured to contain liquid helium to cool the magnet coils. A radiation shield has a radiation shield inner tube encompassing the He tank and spaced from the He inner tube to create a space between the He inner tube and the radiation shield inner tube to reduce an evaporation rate of the liquid helium. The NMR apparatus additionally includes a field shaping device with a magnetic material arranged in the space, in order to shim the homogeneous magnetic field. The field shaping device is fixed in the space so as to be in rigid mechanical contact with the He tank but without contacting the radiation shield.