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The Gerda experiment at Lngs of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the Gerda cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: ( i ) secondary muons from the Cngs neutrino beam (2.2%) and ( ii ) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of I μ 0 = ( 3.477 ± 0 . 002 stat ± 0 . 067 sys ) × 10 − 4 /(s · m 2 ) was found in good agreement with other experiments at Lngs . Combining the present result with those from previous experiments at Lngs the effective temperature coefficient α T , Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio r K / π of 0.10 ± 0.03. [ABSTRACT FROM AUTHOR]

A solution to the problem of disturbing effect of the background Faraday rotation in the cryostat windows on longitudinal magneto-optical Kerr effect (LMOKE) measured under vacuum conditions and/or at low temperatures is proposed. The method for eliminating the influence of Faraday rotation in cryostat windows is based on special arrangement of additional mirrors placed on sample holder. In this arrangement, the orientation of the cryostat window is perpendicular to the light beam direction and parallel to an external magnetic field generated by the H-frame electromagnet. The operation of the LMOKE magnetometer with the special sample holder based on polarization modulation technique with a photo-elastic modulator is theoretically analyzed with the use of Jones matrices, and formulas for evaluating of the actual Kerr rotation and ellipticity of the sample are derived. The feasibility of the method and good performance of the magnetometer is experimentally demonstrated for the LMOKE effect measured in Fe/Au multilayer structures. The influence of imperfect alignment of the magnetometer setup on the Kerr angles, as derived theoretically through the analytic model and verified experimentally, is examined and discussed. [ABSTRACT FROM AUTHOR]

A cold finger vacuum cryostat is described in which a sapphire heat conducting element is used to achieve very fast slew rates for a small sample stage over a wide temperature range with optimal matching to a closed cycle helium refrigerator head. When the set temperature is reached it is maintained with very high stability (±5 mK). The target applications are associated with semiconductor electrical material characterisation measurements which require temperature scanning, e.g., thermally stimulated current, deep level transient spectroscopy, and applications which require annealing followed by rapid transition to lower temperature for measurement. [ABSTRACT FROM AUTHOR]

Results of investigation of a fundamentally new type of cryogenerator in which the energy of the active flow is transferred to a passive flow are presented. The cryogenerator is called rotor-wave generator. A nonlinear mathematical model describing processes that occur in a rotor-wave cryogenerator (RWCG) is developed. Its distinguishing feature is the fact that it takes the properties of the actual gas into account in calculating the integral characteristics of the RWCG and in the method employed by Academician of the Russian Academy of Sciences S. K. Godunov (fracture-disintegration method). Results of calculations are presented as plots of gas parameters in the extreme computational cells, an indicator diagram, and the wave pattern of energy exchange in the RWCG. Analysis of the results obtained for mathematical modeling indicated good convergence with experimental results. Basic processes that occur in the energy-exchange channel of the cryogenerator are brought to light. In our opinion, the type of cryogenerators investigated is of major practical interest. This paper has a direct relationship to the problem of thesearch for optimal production schemes for liquefaction of natural gas. [ABSTRACT FROM AUTHOR]

A portable small liquefier for natural gas or coal-bed methane liquefaction has been designed and tested. The liquefier is very compact, and the compressor is directly mounted on a trailer. The liquefier is based on a mixed-refrigerant liquefaction cycle with R22 precooling. Most of the components in the liquefier are easily available off-the-shelf refrigeration products. An oil-lubricated single-stage R22 screw compressor is used for the mixed-refrigerant compression. An aluminum plate-fin heat exchanger with four flow passages was designed as the core of the cold box. The liquefier was tested for about 4months by circulating pure methane as the natural gas resource. A maximum liquefaction capacity of 15,000Nm3 was achieved with a minimum specific power consumption of about 0.54kWh/Nm3. This liquefier can be used in various applications such as small natural gas or coalbed methane exploitations, distributed peak-shaving, and boil-off gas reliquefaction. These can also be used as a flexible distributed liquefaction center with a set of small liquefiers. [Copyright &y& Elsevier]

The design and operation of a receive-only liquid nitrogen ( \LN2)-cooled coil and cryostat suitable for medical imaging on a 3-T whole-body magnetic resonance scanner is presented. The coil size, optimized for murine imaging, was determined by using electromagnetic (EM) simulations. This process is therefore easier and more cost effective than building a range of coils. A nonmagnetic cryostat suitable for small-animal imaging was developed having good vacuum and cryogenic temperature performance. The \LN2-cooled probe had an active detuning circuit allowing the use with the scanner's built-in body coil. External tuning and matching was adopted to allow for changes to the coil due to temperature and loading. The performance of the probe was evaluated by comparison of signal-to-noise ratio (SNR) with the same radio-frequency (RF) coil operating at room temperature (RT). The performance of the RF coil at RT was also benchmarked against a commercial surface coil with a similar dimension to ensure a fair SNR comparison. The cryogenic coil achieved a 1.6- to twofold SNR gain for several different medical imaging applications: For mouse-brain imaging, a 100-\mu \m resolution was achieved in an imaging time of 3.5 min with an SNR of 25–40, revealing fine anatomical details unseen at lower resolutions for the same time. For heavier loading conditions, such as imaging of the hind legs and liver, the SNR enhancement was slightly reduced to 1.6-fold. The observed SNR was in good agreement with the expected SNR gain correlated with the loaded-quality factor of RF coils from the EM simulations. With the aid of this end-user-friendly and economically attractive cryogenic RF coil, the enhanced SNR available can be used to improve resolution or reduce the duration of individual scans in a number of biomedical applications. [ABSTRACT FROM PUBLISHER]

The isotope ratio analysis of body water often involves large sample numbers and lengthy sample processing. Here we demonstrate the ability of isotope ratio infrared spectroscopy (IRIS) to rapidly and accurately analyse the isotope ratios of water in urine. We analysed water extracted from human urine using traditional isotope ratio mass spectrometry (IRMS) and compared those values with IRIS-analysed extracted water and un-extracted urine. Regression analyses for δ2H and δ18O values between (1) extracted water analysed via IRMS and IRIS and (2) urine and extracted water analysed via IRIS were significant (R2=0.99). These results indicate that cryogenic distillation of urine was not required for an accurate estimate of the isotopic composition of urine when using IRIS. [ABSTRACT FROM AUTHOR]

The article evaluates several cryogenics and vacuum products including cryogenic 44C temperature controller from Cryogenic Control Systems Inc., stainless steel high vacuum gate valves from VAT Inc. and multichannel electron energy analyzer from LK Technologies Inc.

closed cycle cryostat intended for optical and Mössbauer investigations in the temperature range 4.2-300 K is described. Samples are cooled owing to the operation of a two-stage closed-cycle cryogenic refrigerator (CR) based on the Gifford-MacMahon cycle (with a refrigerating capacity of 1 W at T = 4.2 K at the second stage). The minimum temperature reached at the second stage of the CR was 2.7 K. The methods for reducing vibrations transferred from the CR to a sample are described in detail. The design proposed makes it possible to reduce the vibrational broadening of the resonance Mössbauer lines to a level of 10-15% at 5 K, thus exceeding the level of the best cryostat prototypes in the world. [ABSTRACT FROM AUTHOR]

The National High Magnetic Field Laboratory (NHMFL) is designing two series-connected hybrid magnets, one for the Helmholtz Center Berlin (HZB) and the other for the NHMFL. The one for HZB has a horizontal, conical warm bore with a 30 degree opening angle for neutron scattering experiments. The one for the NHMFL has a 40 mm diameter vertical warm bore with a cylindrical profile. The design of the HZB cryostat will be completed this year. In this paper the design of the HZB cryostat is presented. The results of a structural analysis performed for normal operation and for fault scenario are discussed. The main features of the NHMFL cryostat are described shortly in the introduction section. [ABSTRACT FROM AUTHOR]

A collaboration between NSCL and Jlab has developed the reference design and coil winding for Jlab's Super High Momentum Spectrometer (SHMS) horizontal bend magnet. A warm iron "C" type superferric dipole magnet will bend the 12 GeV/c particles horizontally by 3° to allow the SHMS to reach angles as low as 5.5°. This requires an integral field strength of up to 2.1 T.m. The major challenges are the tight geometry, high and unbalanced forces and a required low fringe field in primary beam path. A coil design based on flattened SSC Rutherford cable that provides a large current margin and commercially available fiberglass prepreg epoxy tape has been developed. A complete test coil has been wound and will be cold tested. This paper present the modified magnet design includes coil forces, coil restraint system and fringe field. In addition, coil properties, quench calculations and the full mechanical details are also presented. [ABSTRACT FROM AUTHOR]

Abstract: The vibrations of the cold finger of a low-vibration helium pulse-tube cryostat are measured from 1Hz to 20kHz using an optical interferometer specially designed to measure small amplitude vibrations at high frequencies in the presence of large vibrations at lower frequencies. While the vibrational amplitude is dominated by the contribution at the fundamental compressor frequency of 1.4Hz, the pulse tube contributes mechanical noise at frequencies up to 15kHz, where the spectral density is measured to be 4×10−12 m/Hz1/2. Root-mean-squared vibration amplitudes of 5.2μm and 3μm are measured along perpendicular axes in the horizontal plane, and 1.0μm in the vertical direction. The effect of a suspended sample holder for the purpose of attenuating high-frequency vibrations is evaluated. Finally, the cryostat is shown to be considerably noisier than typical laboratory floors. [Copyright &y& Elsevier]

Magnetometers based on Superconducting Quantum Interference Device (SQUID) are widely employed in high sensitivity magnetometry. In particular, new multichannel systems for biomagnetic applications require many sensors which are very close to each other giving the crosstalk disturbance between the neighboring channel. Here, we present experimental results about a fully integrated dc-SQUID magnetometer, based on niobium technology, having a suitable design which allows to reduce crosstalk due to both the feedback coil and wires. The crosstalk level measurements relative to a particular arrangement of sensors are reported. In such configuration, four magnetometers are placed over a square board 30 mm in side with a distance between their sensor centers of 14 mm. The measurements have been performed in a 4He cryostat at T = 4.2 K in a flux-locked loop configuration using a readout electronics with a direct coupled scheme. The experimental data have shown a substantial reduction of crosstalk among neighboring sensors with respect to a traditional feedback coil. Furthermore, the field noise measurements have ensured that the new pickup and feedback coils design does not introduce any noise level degradation. [ABSTRACT FROM AUTHOR]

A compact autonomous 3He cryostat inserted into a two-stage refrigerator with an impulse tube is described. The cryostat contains baths filled with 4He and 3He and evacuated with cryosorbers to temperatures of ∼1 and ∼0.35 K, respectively. The low temperature is maintained for 6–8 h at an amount of liquid 3He filling the cryostat of ∼0.035 mol. The dimensions of the insert (below the upper flange) are 49 mm (diameter) and 720 mm (length). The insert is introduced into a hermetically sealed tube-well filled with a heat-exchange gas during operation, which promotes the heat removal to levels of 45–50 K (the first stage of the impulse tube) and 3–4 K (the second stage of the impulse tube). The cryostat can be mounted in and extracted from both the warm cryostat and the cryostat cooled to low temperatures. [ABSTRACT FROM AUTHOR]

Historically, large germanium arrays for field applications have consisted of multiple detectors each housed in their own cryostat. In order to ruggedize the detectors for field use these cryostats have had additional support material introduced that significantly impacted cryogenic performance. This paper presents the development of a new cryostat design suitable for deployment of ∼10 kg of high purity germanium detectors that achieves outstanding cryogenic performance (∼5 W at 80 K) while providing the high detection efficiency required for stand-off measurements and the ruggedization required for use in a variety of field applications. [ABSTRACT FROM AUTHOR]

We present the design of a confocal microscope adapted for optical spectroscopy and imaging at cryogenic temperatures. This system is based on the existing approach of partly inserting the optical components of the microscope inside a helium-bath cryostat. It provides a spatial resolution approaching the diffraction limit with a mechanical stability allowing uninterrupted integration times exceeding 10 h and allows keeping track of a single emitter for unlimited periods of time. Furthermore, our design allows scanning the excitation spot and detection area independently of the sample position. This feature provides the means to perform probeless transport experiments on one-dimensional nanostructures. The scanning capabilities of this microscope are fully detailed and characterized using the photoluminescence of single nitrogen dyads at 4.5 K. [ABSTRACT FROM AUTHOR]

The development of High Temperature Superconductors (HTS) conductors makes it possible to build very high field superconducting magnets up to at least 25 T. Previously, the only way to obtain a steady field of 25 T for research would be to use water cooled copper solenoids. To achieve 25 T in a 50 mm working space would require about 10 MW of power with a large water cooling plant to carry away the heat. With such high powers involved it is difficult to have a stable and quiet magnetic field environment in which to make sensitive measurements such as NMR. Both capital and operating costs are high so few such facilities exist worldwide. This makes a superconducting magnet of 25 T a very attractive proposition. Figure 1 shows that the critical current of HTS as compared to NbTi and NbSn. The latter can be used up to a limit of about 20 T at 4.2 K. The HTS on the other hand shows the potential of much higher fields... [ABSTRACT FROM AUTHOR]

A pulsed valve connected to a closed-cycle cryostat was optimized for producing helium droplets. The pulsed droplet beam appeared with a bimodal size distribution. The leading part of the pulse consists of droplets suitable for doping with molecules. The average size of this part can be varied between 104 and 106 helium atoms, and the width of the distribution is smaller as compared to a continuous-flow droplet source. The system has been tested in a single pulse mode and at repetition rates of up to 500 Hz with almost constant intensity. The droplet density was found to be increased by more than an order of magnitude as compared to a continuous-flow droplet source. [ABSTRACT FROM AUTHOR]

Automated precision measurement setups for electrical resistivity of eight metallic samples simultaneously and thermoelectric power of different types of samples in the temperature range of 5–325 K have been developed. The details of the setups and their capabilities have been described. Usually each run takes nearly 5 h and typical error is within 3% and 4%, respectively. The results of high purity Nb and Pt samples are used as examples to demonstrate this. [ABSTRACT FROM AUTHOR]

AbstractThe Low Temperatures Laboratory of CEA/Grenoble (France) is involved in the development of cryogenic systems for inertial fusion since a ten of years. A conceptual design for the cryogenic infrastructure of the Laser MegaJoule (LMJ) facility has been proposed. Several prototypes have been designed, built and tested like for example the 1500 bars cryo compressor for the targets filling, the target positioner and the thermal shroud remover.The HIPER project will necessitate the development of such equipments. The main difference is that this time, the cryogenic targets are direct drive targets. The first phase of HIPER experiments is a single shot period. Based on the experience gained the last years, not only by our laboratory but also by Omega and G.A teams, we could design the new HIPER equipments for this phase.Some experimental results obtained with the prototypes of the LMJ cryogenic system are given and a first conceptual design for the HIPER single shot cryogenic system is shown. [ABSTRACT FROM AUTHOR]

Abstract: This document describes the design and the prototyping performed at CEA/SBT in partnership with AIR LIQUIDE of a high frequency large cooling power pulse tube. Driven at 58Hz by a 7.5kW flexure bearing pressure wave generator, this system provides a net heat lift of 210W at 65K. The phase shift is obtained by an inertance and a buffer volume. This type of cryogenic cooler can be used for on site gas liquefaction or drilling site and for high temperature superconductivity power device cooling (transmission lines, large generators, fault current limiters). In this paper, we focus on two essential points, the regenerator and the flow straightener. The regenerator is a key component for good performance of the pulse tube cooler. It must have a large thermal inertia, a low dead volume, a good heat transfer gas/matrix and at the same time, small pressure drop. In the present case and unlike typical moderate cooling power pulse tubes, the regenerator is very compact. However, the resulting conductive losses remain negligible compared to the cooling power targeted. The goal of the flow straightener is to avoid as much as possible any jet stream effect and to guarantee the uniformity of the velocity field at both ends of the pulse tube. Indeed multi-dimensional flow effects can significantly impact the performances of the machine. [Copyright &y& Elsevier]

For testing rapidly-cycled superconducting magnets in the framework of the FAIR project (Facility for Antiprotons and Ion Research) a test facility was set up at GSI to test model and prototype superconducting magnets for different machines (SIS100, SIS300, Super-FRS). We are able to perform the following magnet tests: quench training, magnetic measurements, measurements of AC losses (calorimetric and V-I methods), temperature distributions in the magnet, and long-term stability tests. The forced-flow and bath-cooled scheme can be applied for the superconducting magnets. The facility consists of the following components: a refrigerator (400 W at 4 K); a distribution box for different cooling schemes (supercritical and two-phase flow); 2 feed-boxes providing electrical and cryogenic supply for the magnets; an all-purpose horizontal magnet cryostat which can be used for all kinds of different magnets (max. 3 m length and 0.8 m diameter); a power converter (11 kA) including the quench protection system; a quench detection system adapted from the LHC-series test facilities. The results of the AC loss measurements and the quench training for the first tested superconducting magnet are presented. [ABSTRACT FROM AUTHOR]

In order to apply resistive superconducting fault current limiters into electric power systems, the urgent issues to be settled are as follows, such as initial installation price of SFCL, operation and maintenance cost due to ac loss of superconductor and the life of cryostat, and high voltage and high current problems. The ac loss and high cost of superconductor and cryostat system are main bottlenecks for real application. Furthermore in order to increase voltage and current ratings of SFCL, a lot of superconductor components should be connected in series and parallel which resulted in extreme high cost. In addition, the method to quench all components at the same instant needs very sophisticated skill and careful operation. Due to these problems, the practical applications of SFCL were pending. Therefore, in order to make practical SFCL, the price of SFCL should be lowered and should meet the demand of utilities. LSIS and KEPRI designed novel hybrid SFCL which combines superconductor and conventional electric equipment including vacuum interrupter, power fuse and current limiting reactor. The main purpose of hybrid SFCL is to drastically reduce total usage of superconductor by adopting current commutation method by use of superconductor and ultra fast switch. Consequently, it was possible to get the satisfactory test results using this method, and further works for field tests are in the process. [ABSTRACT FROM AUTHOR]

The ATLAS Experiment at LHC, CERN will utilize a large, superconducting, air-cored toroidal magnet system with a long Barrel Toroid and two End Cap Toroids. Each End Cap Toroid contains eight racetrack coils mounted as a single cold mass in a cryostat vessel of approximately 10 m diameter and 5 m length. The operating current is 20.5 kA at 0.25 GJ stored energy and a peak field of 4.1 T in the windings. This paper presents the status of the End Cap Toroid Project. Final integration of the two cold masses, 120 tons each, into their respective vacuum cryostats is described. The specialized techniques, procedures and tooling infrastructure required for these operations are explained. Pre-installation cooldown to 85 K is reported. Installation of the toroids in the ATLAS cavern 100m underground will be described. The final interfacing to the Barrel Toroid and services in the cavern will be reviewed along with preparations for final test and commissioning. [ABSTRACT FROM AUTHOR]

Abstract   The CUORE detector, to be installed in 2010 at LNGS, is made of 988 TeO2 crystals to be cooled to 10 mK. It consists of a large cryogen-free cryostat cooled by five pulse tubes and one high-power specially designed dilution refrigerator (R. Ardito et al. in http://arxiv.org/abs/hep-ex/0501010, [2005]). The cryostat is ∼ 3 m high and has a diameter of ∼ 1.6 m. About 5 tons of lead shielding are to be cooled to below 1 K and a mass of 1.5 ton must be cooled to 10 mK. Some tie-rods sustain the different parts of the experiment. One end of each rod is at low temperature (10 mK for the detector frame, 50 mK for the coldest radiation shield, 700 mK for the shield linked to the still) with the other end usually at room temperature. A thermalization of the rods at the temperature of the first stage of the pulse tubes will be realized. Hence the value of the thermal conductivity of the material up to room temperature is important. At the lowest temperatures, the thermal conductivity has great influence in establishing the thermal load on the dilution refrigerator. The thermal conductivity of the structural material candidates for such tie-rods is usually known down to 4.2 K. Here we present data of thermal conductivity for the Ti6Al4V alloy below its superconductive transition temperature (4.38 K). A comparison over the full temperature range of operation is also done with other materials, such as 316 stainless steel and Torlon, candidates for the realization of the tie-rods. [ABSTRACT FROM AUTHOR]

Abstract: We developed a helium circulating system that re-liquefies all the evaporating helium gas and consumes far less power than conventional systems, because warm helium gas at about 40K collected high above the surface of the liquid helium in the Dewar is used to keep the Dewar cold, and because cold helium gas just above the liquid helium surface is collected and re-liquefied while still cold. A special transfer tube with multi-concentric pipes was developed to make the system operate efficiently. The system can produce up to 35.5l/D of liquid helium from the evaporated helium using two 1.5W@4.2K GM cryocoolers. [Copyright &y& Elsevier]

The design of a compact ultrahigh-vacuum nitrogen-free helium cryostat is described. The volume of the helium vessel of the cryostat is 2.7 l, and the time of operation after filling it with liquid helium is >65 h. The cryostat satisfies the requirements imposed on ultrahigh-vacuum systems, allows heating to 200°C, and ensures operation at an evacuation level of 10−10 Torr. [ABSTRACT FROM AUTHOR]

Abstract: We describe a simple and efficient improvement to the Martin–Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector’s signal increases up to ∼10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities. [Copyright &y& Elsevier]

Cheap to make and easy to shape, Magnesium Diboride (MgB2) throws the field of applied superconductivity wide open. Great efforts have been made to develop a superconducting fault current limiter (SFCL) using MgB2. With a superconducting transition temperature of 39 K, MgB2 can be conveniently cooled with commercial cryocoolers. A cryogenic desktop test system, an ac pulse generation system and a real time data acquisition program in LabView/DAQmx were developed to investigate the quench behavior of MgB2 wires under pulse overcurrents at 25 K in self-field conditions. The experimental results on the current limitation behavior show the possibilities for using MgB2 for future SFCL applications. [ABSTRACT FROM AUTHOR]

SMES is a potential solution for power quality issues. The development of a 1 M J/0.5 MVA SMES is now at its final stage and the device will be put into operation in a live power grid of 10 kV in late of 2006 at a substation in the suburb of Beijing, China. The design and analysis of the SMES coil has been completed and magnetic flux density distribution of and electromagnetic force on the coil has been analysed by means of FEM. The cryogenic system adopts bath cooling method and employs four cryo-coolers to re-liquefy the evaporated helium. And HTS current leads are utilized to reduce heat loss. [ABSTRACT FROM AUTHOR]

Superconducting magnetic energy storage (SMES) is more fast response, economical, and environment-friendly than uninterruptible power supply (UPS) using the battery. And the SMES not only has the ability to control active and reactive power simultaneously, but also has a long life time because the superconducting magnet does not have degradation problem which the battery has. Therefore, the SMES is a candidate for instead of the UPS using the battery. The SMES needs cryogenic system without exception. A conduction cooling system that has a simple, light and small structure is well adapted to high temperature superconducting (HTS) SMES. The cryogenic conduction cooling system is needed some technologies such as insulation, vacuum, and thermal analysis. Conduction heat is mainly transferred by cooler port, access port, support bar, etc., and radiation heat is transferred by vacuum chamber, thermal shield and HTS coil surface. The heat loads through the conduction and radiation of cryostat are calculated. Radiation shield heat load, temperature of HTS coil and conduction copper plate are estimated and measured. A cryopumping effect of cooled radiation shield was observed. A current lead and HTS coil heat load was evaluated to maintain HTS coil temperature was under 20 K. [ABSTRACT FROM AUTHOR]