Abstract: A quench protection arrangement for a superconducting magnet is disclosed. The arrangement comprises: a superconducting magnet comprising a plurality of magnet sections; a plurality of varistors, wherein each of the plurality of varistors is electrically connected in parallel across a respective one of the plurality of magnet sections; and a heater arrangement electrically connected to the plurality of varistors and configured to apply heat to each of the plurality of magnet sections in response to a change in a voltage across any one or more of the plurality of varistors. A method of protecting a superconducting magnet is also disclosed.

Abstract: Disclosed preamplifier circuit comprises amplifier arranged in first current path between input node and output node of the preamplifier circuit. Feedback capacitor is arranged in second current path between said input and output nodes. Feedback circuit having adjustable transfer function is arranged in third current path between said input and output nodes. Reset switch arranged in said third current path enables selectively coupling output of the feedback circuit to input of the amplifier and decoupling output of the feedback circuit from input of the amplifier. Loop controller is arranged selectively, in dependence of voltage in the preamplifier circuit, one of open reset switch to set preamplifier circuit in normal operating mode and close reset switch to set preamplifier circuit in reset mode. Loop controller is arranged to adjust the transfer function of the feedback circuit at least in part in dependence of the current operating mode of the preamplifier circuit.

Abstract: A system for preventing collisions between components in a particle beam instrument is disclosed. The system is particularly beneficial in use with instruments wherein moveable components are used within a chamber that obscures them from being viewed from outside the chamber. The system comprises: a capacitance sensor configured to monitor the capacitance between a first component and a second component of the instrument, and a proximity module configured to: derive a capacitance parameter from the monitored capacitance between the first component and the second component; and output a proximity alert signal in accordance with a comparison between the derived capacitance parameter and a predetermined capacitance parameter threshold value.

Abstract: A method and system for processing a diffraction pattern image obtained in an electron microscope are disclosed.

Abstract: Disclosed is a semiconductor radiation detector assembly including a detector chip having a front side for receiving radiation and a back side; and a flexible substrate including a center portion having its front side attached to the back side of the detector chip and a plurality of strips extending from the center portion and bent to protrude away from the detector chip, wherein the flexible substrate includes a plurality of conductive tracks that extend on a surface of the strips from the center portion towards lateral ends of the strips for electrical coupling and mechanical attachment to one of a plurality of contact pins, and wherein the detector chip is electrically coupled to at least one of the conductive tracks.

Abstract: A cryogenic cooling system is provided comprising a first stage 6, a second stage 7, and a third stage 8, wherein the second stage 7 is arranged between the first stage 6 and the third stage 8. A first dilution unit 12 is provided comprising a first still 11 and a first mixing chamber 13, wherein the first still 11 is thermally coupled to the first stage 6 and the first mixing chamber 13 is thermally coupled to the third stage 8. A second dilution unit 32 is further provided comprising a second still 31 and a second mixing chamber 33, wherein the second still 31 is thermally coupled to the first stage 6 and the second mixing chamber 33 is thermally coupled to the second stage 7.

Abstract: A window member for separating an internal environment of an x-ray device from an environment external to the x-ray device is provided. The window member comprises a substrate and a coating layer disposed upon a surface of the substrate. The substrate is formed from a polycrystalline material and is substantially transparent to low-energy x-rays. The coating layer is non-porous, covers the crystal grains at the surface of the substrate and extends into the grain boundaries therebetween, such that the coating layer forms an impermeable barrier between the substrate and the external environment.

Abstract: A cryogenic refrigeration system is provided having particular application in cooling a Magnetic Resonance Imaging system. The cryogenic refrigeration system comprises a conduit arranged as a cooling circuit through which a coolant fluid is pumped, the conduit being in thermal communication with a least one cooled stage for cooling the coolant fluid to a first temperature, and wherein the conduit comprises a cryotrap in communication with the coolant fluid, the cryotrap being operable to remove contaminants from the coolant fluid by cryogenic pumping. The conduit further comprises a flow impedance for cooling the coolant fluid to a second temperature lower than the first temperature, and a hydrogen filter upstream of the flow impedance and in communication with the coolant fluid, the hydrogen filter being cooled to a temperature below the freezing point of hydrogen in the coolant fluid and operable to remove contaminant hydrogen from the coolant fluid.

Abstract: A method is provided for performing electron diffraction pattern analysis upon a sample in a vacuum chamber of a microscope. Firstly a sample is isolated from part of a specimen using a focused particle beam. A manipulator end effector is then attached to the sample so as to effect a predetermined orientation between the end effector and the sample. With the sample detached, the manipulator end effector is rotated about a rotation axis to bring the sample into a predetermined geometry with respect to an electron beam and diffraction pattern imaging apparatus so as to enable an electron diffraction pattern to be obtained from the sample while the sample is still fixed to the manipulator end effector. An electron beam is caused to impinge upon the sample attached to the manipulator end effector so as to obtain an electron diffraction pattern.

Abstract: A cryogenic cooling system can include a cooling device and a sample holder. The system can also include a first optical member having a first aperture and a first collimator, where the first collimator is positioned to collimate the light. The system can further include a second optical member having a second aperture and a second collimator where the second collimator is positioned to collimate the light, the first optical member being mounted to the cooling device and the second optical member being mounted to the sample holder. When the sample holder is mounted to the cooling device, a relative position of the first optical member and the second optical member allows the light to pass between the first and second apertures via the first collimator and second collimator separated by a physical gap to allow optical communication between the first optical member and the second optical member.

Abstract: A method and apparatus for analysis of a specimen in a microscope are provided. A first survey is performed that collects analytical data from a region of interest on the specimen surface using a first set of conditions. A second survey is performed that collects additional analytical data from selected parts of the region of interest on the specimen surface using a second set of conditions, different from the first set of conditions. The analytical data from the first survey is used to select the parts used for data collection in the second survey and to decide the order in which they are used.

Abstract: A method for forming a gas gap heat switch is provided comprising the following steps: (a) providing first and second conductors, and first and second connecting members, wherein the connecting members each have a thermal conductivity at least five times smaller than that of the conductors when at a temperature of 100K; (b) fusing the first conductor to the first connecting member and the second conductor to the second connecting member; (c) aligning the conductors such that the first and second conductors extend along a common major axis; (d) bringing proximal ends of the aligned conductors into contact with each other when said conductors are at a first temperature; and (e) joining the first connecting member to the second connecting member so as to form a chamber around at least the proximal ends of the conductors.

Abstract: A cryogenic cooling system can include a cooling device and a sample holder. The system can also include a first optical member having a first aperture and a first collimator, where the first collimator is positioned to collimate the light. The system can further include a second optical member having a second aperture and a second collimator where the second collimator is positioned to collimate the light, the first optical member being mounted to the cooling device and the second optical member being mounted to the sample holder. When the sample holder is mounted to the cooling device, a relative position of the first optical member and the second optical member allows the light to pass between the first and second apertures via the first collimator and second collimator separated by a physical gap to allow optical communication between the first optical member and the second optical member.

Abstract: A pulse tube refrigerator (PTR) comprising a pedestal head and a regenerator tube assembly is provided having particular application in cooling a Magnetic Resonance Imaging system. The PTR comprises a pedestal head and at least one cooled stage, the at least one cooled stage being mounted to a distal end, with respect to the pedestal head, of each of an associated regenerator tube and an associated pulse tube, the associated regenerator tube and associated pulse tube together providing pressurized coolant gas to the at least one cooled stage, wherein the associated regenerator tube and the associated pulse tube are elongate along substantially parallel axes; and further arranged, wherein, the displacements of the distal ends of each of the associated regenerator tube and the associated pulse tube in response to the cyclical changes in coolant pressure, are substantially the same when the pulse tube refrigerator is in use.

Abstract: An assembly for operating a cryocooler pedestal is provided. The assembly is operable when in use to provide a cryocooler pedestal with cyclical gaseous connection to high pressure and low pressure gas supply lines, and has a return conduit through which gas is caused to flow from the cryocooler pedestal into the low pressure supply line. The assembly further comprises a dispersion chamber adjacent the return conduit and in flow communication therewith through a plurality of orifices so as to reduce acoustic noise. The assembly has particular application in cooling a Magnetic Resonance Imaging system.

Abstract: A method is provided of measuring the mass thickness of a target sample for use in electron microscopy. Reference data are obtained which is representative of the X-rays (28) generated within a reference sample (12) when a particle beam (7) is caused to impinge upon a region (14) of the reference sample (12). The region (14) is of a predetermined thickness of less than 300 nm and has a predetermined composition. The particle beam (7) is caused to impinge upon a region (18) of the target sample (16). The resulting X-rays (29) generated within the target sample (16) are monitored (27) so as to produce monitored data. Output data are then calculated based upon the monitored data and the reference data, the output data including the mass thickness of the region (18) of the target sample (16).

Abstract: A method is provided for processing a spectrum, obtained using a particle detection system, so as to reduce spectrum artifacts arising from unresolved particle events in the detection system. An input spectrum is obtained which contains artifacts due to “pile up” in the detector. A first effect upon the input spectrum of pairs of unresolved particle events is evaluated and a first corrected input spectrum is generated which comprises the input spectrum with the first effect removed. The effect of a pairs of unresolved particle events is then evaluated for this first corrected input spectrum so as to generate a second corrected input spectrum which comprises the input spectrum with the second effect removed. An output spectrum is then generated based upon a combination of the first and second corrected input spectra. The use of the method in improving sum spectra is also discussed.

Abstract: Cryogenic cooling apparatus is disclosed for cooling a target region using the demagnetization cooling effect. The apparatus has a primary magnet for providing a magnetic field within the target region and a demagnetization magnet arranged to selectively provide conductive cooling to the target region. A primary shielding magnet substantially cancels the magnetic field from the primary magnet at least at a first position between the primary and demagnetization magnets. A demagnetization shielding magnet substantially cancels the magnetic field from the demagnetization magnet at least at the first position between the primary and demagnetization magnets. Each of the primary shielding magnet and demagnetization shielding magnet comprises a cylindrical superconducting coil having a geometric envelope which encloses the primary magnet and demagnetization magnet respectively. A conductive cooling assembly provides conductive cooling to each of the magnets.

Abstract: Improvements for rapidly calibrating and automatically operating a scanning probe microscope are disclosed. A central component of the SPM is the force transducer, typically a consumable cantilever element. By automatically calibrating transducer characteristics along with other instrumental parameters, scanning parameters can be rapidly and easily optimized, resulting in high-throughput, repeatable and accurate measurements. In contrast to dynamic optimization schemes, this can be accomplished before the surface is contacted, avoiding tip or sample damage from the beginning of the measurement process.

Abstract: This invention relates to an optical light beam positioning system that enables the combination of two or more light beams of different wavelengths to be focused onto a probe or sample of a scientific instrument, such as an atomic force microscope, for a number of specific uses typical to AFMs, like measuring the deflection or oscillation of the probe and illuminating an object for optical imaging, and less traditional ones like photothermal excitation of the probe, photothermal activated changes in the sample, photothermal cleaning of the probe and photochemical, photovoltaic, photothermal and other light beam induced changes in the sample. The focused light beams may be independently positioned relative to each other.