Production and validation of scintillating structural components from low-background Poly(ethylene naphthalate)

Poly Ethylene Naphthalate (PEN) is an industrial polymer plastic which is investigated as a low background, transparent, scintillating and wavelength shifting structural material. PEN scintillates in the blue region and has excellent mechanical properties both at room and cryogenic temperatures. Thus, it is an ideal candidate for active structural components in experiments for the search of rare events like neutrinoless double-beta decay or dark matter recoils. Such optically active structures improve the identification and rejection efficiency of backgrounds events, like this improving the sensitivity of experiments. This paper reports on the production of radiopure and transparent PEN plates These structures can be used to mount germanium detectors operating in cryogenic liquids (LAr, LN). Thus, as first application PEN holders will be used to mount the Ge detectors in the Legend-200 experiment. The whole process from cleaning the raw material to testing the PEN active components under final operational conditions is reported.

Spatial and spectral features of the luminescence of liquid nitrogen stimulated by infrared lasers

Spectral features of cryogenic liquids, especially nitrogen, seem to be clearly investigated due to the wide application in science. On the other hand, material properties can really be different under intensive laser irradiation. During irradiation of liquid nitrogen with pulsed (pulse duration 20 ns) YaG: Nd 1064 nm laser with average power of 0.3 W we have found bright luminescence in the visible region with five narrow spectral lines. This phenomenon can be explained by the multiphoton excitation of nitrogen molecules and ions with infrared photons. Its spatial and spectral characteristics are attributed to Amplified Spontaneous Emission. The main features include super-linear dependence of the emission intensity on the intensity of the excitation radiation, limited amount of narrow spectral bands and conical geometry of the emission with the clear separation of the cones in correspondence with the spectral lines of the emission. This phenomenon manifests liquid nitrogen as the convenient substance of Kerr type for studies of various non-linear optical processes by means of nanosecond lasers instead of femtosecond lasers applied usually for these purposes.

Comparative study on thermodynamic characteristics of composite thermal insulation systems with liquid methane, oxygen, and hydrogen

Composite passive insulation technology has been proved to be an effective method to reduce heat leakage into the cryogenic storage tank. However, the current related research mainly focused on liquid hydrogen (LH2). The thermophysical properties of different cryogenic liquids and the thermal insulation materials at different temperatures are significantly different, so whether the results related to LH2 are applicable to other cryogenic liquids remains to be further determined. In fact, the insulation technology of LH2 itself also needs further study. In this paper, a thermodynamic calculation model of a composite insulation system including hollow glass microspheres (HGMs), multilayer insulation (MLI), and self-evaporating vapor cold shield (VCS) has been established. The accuracy of the calculation model was verified by the experimental results, and a comparative study on thermodynamic characteristics of the composite thermal insulation system with liquid methane, liquid oxygen (LO2), and LH2 was carried out. The results show that the heat leakage reduction of the proposed system for liquid methane, LO2 and LH2 is 25.6%, 29.7% and 64.9% respectively compared to the traditional SOFI+MLI system (1*10−3 Pa). The type of liquid and the insulation system structure has a relatively large influence on the VCS optimal position. While for a specific insulation system structure, the insulation material thickness, storage pressure, and hot boundary temperature have a weak influence on the VCS optimal position.

A Novel Long-Duration Hydrogen Storage Concept Without Liquefaction and High Pressure Suitable for Onsite Blending

Hydrogen is typically stored as a low-pressure cryogenic liquid or as a high-pressure gas. Both approaches come with technical challenges that complicate the implementation of such systems at the actual power plant scale. Cryogenic liquids can provide high energy and volume densities but require complex storage systems to limit boil-off. That makes such liquid tanks complex, large, and heavy which in turn drives up capital cost. Furthermore, expensive liquefaction equipment is required, too. The liquefaction process is highly energy-intensive, approximately 35% of the fuel energy, hence, reduces the net performance of gas turbine power plants using such hydrogen storage approaches. Conversely, high-pressure gas storage bottles are less complex and can be kept at room temperature. However, they require a thick wall to withstand the high pressure which makes them considerably heavy as well. Furthermore, the energy densities associated with gas storage are dramatically lower than for cryogenic liquids, even at high pressures up to 700 bar. The present study presents and discusses a novel concept for storing hydrogen to be used in gas turbine power plants. Proposed technology enables the storage of hydrogen close to cryogenic density without the need for high pressure or liquefaction and the delivery to the gas turbine asset can be at engine pressure so that no gas compression is required. It is believed that the capacity of the storage system scales easily so that hydrogen can be stored for long durations from daily to monthly cycles which correspond to 10 to 100 hours, respectively. Besides a SWOT analysis, a system will be described that would integrate into the existing OEM infrastructure and allows the blending of hydrogen and natural gas between ratios between 30% and 100%. Specifications will be provided for the storage system and analyzed for a gas turbine power plant with 100 MW.

Nonlinear oscillations of the interface of two liquids at the angular oscillations of the tank

The development of rocket and space technology in recent years has led to the widespread use of various cryogenic liquids. To increase the shelf life of cryo-products on board spacecraft or in tankers of future space filling stations, it is proposed to create a certain stock of cryo-product, which is simultaneously in a two-phase or three-phase state and forms layers of liquid. The paper considers the problem in a nonlinear formulation about the oscillations of the interface of a two-layer liquid in an arbitrary axisymmetric cavity of a solid body performing angular oscillations around a horizontal axis. For the considered class of cavities with an arbitrary bottom and a lid, the nonlinear problem is reduced to the sequential solution of linear boundary value problems. Nonlinear differential equations describing the oscillations of the interface between two liquids in the vicinity of the main resonance are obtained. In the case of a circular cylindrical cavity with flat bottoms, solutions of boundary value problems in the form of cylindrical functions were used to calculate linear and nonlinear hydrodynamic coefficients depending on the depth and density of the upper liquid.

Characterization of high-purity germanium detectors with amorphous germanium contacts in cryogenic liquids

For the first time, planar high-purity germanium detectors with thin amorphous germanium contacts were successfully operated directly in liquid nitrogen and liquid argon in a cryostat at the Max-Planck-Institut für Physics in Munich. The detectors were fabricated at the Lawrence Berkeley National Laboratory and the University of South Dakota, using crystals grown at the University of South Dakota. They survived long-distance transportation and multiple thermal cycles in both cryogenic liquids and showed reasonable leakage currents and spectroscopic performance. Also discussed are the pros and cons of using thin amorphous semiconductor materials as an alternative contact technology in large-scale germanium experiments searching for physics beyond the Standard Model.