Commercial Xenon Research Articles

Experiment and optimization of a large scale xenon/krypton cryogenic distillation system

A highly efficient cryogenic distillation system has been designed, developed and assessed to remove radioactive krypton-85 (85Kr) from xenon (Xe), which is commonly used as a valuable medium for dark matter detectors. By using the self-designed distillation system, the concentration of krypton (Kr) in a commercial xenon product can be reduced from 10−9 to 10−12 mol/mol with 99% xenon collection efficiency at maximum flow rate of 5 kg/h. Over 1000 kg of xenon has been purified and employed as the detection medium in project Panda X, the first dark matter detector developed in China. In this present paper, detailed process simulation was conducted to refine the working parameters and to define the optimum operating conditions for the cryogenic distillation system. The predicted results were compared with those of experimental data obtained from the distillation system. The influence of comprehensive factors was investigated. Simultaneously, a dynamic model for the cryogenic distillation system was established to provide an in depth analysis of the dynamic characteristics of the system.

PandaX-4T cryogenic distillation system for removing krypton from xenon.

An efficient cryogenic distillation system was designed and constructed for the PandaX-4T dark matter detector based on the McCabe-Thiele method and the conservation of mass and energy. This distillation system is designed to reduce the concentration of krypton in commercial xenon from 5 × 10-7 to ∼10-14 mol/molwith 99% xenon collection efficiency at a maximum flow rate of 10 kg/h. The offline distillation operation has been completed and 5.75 tons of ultra-high purity xenon was produced, which is used as the detection medium in the PandaX-4T detector. The krypton concentration of the product xenon is measured with an upper limit of 8.0 ppt. The construction, operation, and stable purification performance of the cryogenic distillation system are studied with the experimental data, which is important for theoretical research and distillation operation optimization.

Light-Emitting Diode-Based Pulsed Illumination Source for Continuous, Cycle-Resolved Spray Measurements

This paper presents a modular, high-powered light emitting diode (LED)-based illumination source to be used for spray measurements of the liquid phase via Mie scattering. The recent availability of consumer-grade LED arrays with average rated radiant powers of more than 100 W have enabled lower-cost designs than were possible with the previous laser illuminants. Flash tubes suffer from a non-constant rate of emission intensity and a fixed discharge time,which can be a restricting factor, especially with multiple injections. The narrow spectral distributionof LEDs,with a full width at half maximum of 17nm,aids in distinguishing the measurement signal from unwanted background noise.Using frame- synchronous LED pulse generation at repetition rates of 100 kHz,it is possible to record both arbitrarily spaced multiple injections as well as consecutive working cycles, for example ininternal combustion engines. Pulse durations are currently variable in the range 1-78 μs. Luminous flux is boosted by driving the light source at a significantly higher current and voltage as compared to the continuously rated specifications, which results in a high temporal resolution,as exposure times as low as oneμs provide ample recorded intensities. Benchmarks based on a commercial xenon flash tube and laser diode demonstrate the design’s versatility along with first applications in an optically accessibly research engine.

Design and commissioning of the PandaX-4T cryogenic distillation system for krypton and radon removal

An online cryogenic distillation system for the removal of krypton and radon from xenon was designed and constructed for PandaX-4T, a highly sensitive dark matter detection experiment. The krypton content in a commercial xenon product is expected to be reduced by 7 orders of magnitude with 99% xenon collection efficiency at a flow rate of 10 kg/h by design. The same system can reduce radon content in xenon by reversed operation, with an expected radon reduction factor of about 1.8 in PandaX-4T under a flow rate of 56.5 kg/h. The commissioning of this system was completed, with krypton and radon operations tested under respective working conditions. The krypton concentration of the product xenon was measured with an upper limit of 8.0 ppt.

Mechanical and thermal characterization of a novel nanocomposite thermal interface material for electronic packaging

This paper presents a novel nanocomposite thermal interface material (Nano-TIM) consisting of a silver coated polyimide network and the indium matrix. One of the potential applications of this Nano-TIM is for heat dissipation in integrated circuits and electronic packaging. The shear strength of the Nano-TIM was investigated with DAGE-4000PSY shear tester. The shear strength of Nano-TIM is 4.5MPa, which is 15% higher than that of the pure indium thermal interface material. The microstructure of cross-section and fracture surface was studied using Scanning Electron Microscopy (SEM). SEM pictures show a uniform polymer fiber distribution and solid interface between silver coated fibers and indium matrix. The thermal fatigue resistance of the Nano-TIM was evaluated by monitoring the variation of thermal interface resistance during the thermal cycling test (−40 to 125°C). The thermal interface resistance was measured with a commercial xenon flash instrument after 100, 200, 300, 400, 500, and 1000 temperature cycles. The results of thermal cycling test show that Nano-TIM presented consistent reliability performance with pure indium. Furthermore, the cooling effect of Nano-TIM was demonstrated through measuring the power chip temperature in the die attached structure by using an Infrared Camera. In the test, the Nano-TIM shows a comparable cooling effect to pure indium TIM for die attach applications in electronics packaging.

Large scale xenon purification using cryogenic distillation for dark matter detectors

A high efficiency cryogenic distillation system for removal of radioactive krypton-85 (85Kr) from commercially available xenon (Xe) has been designed, developed and assessed to meet the requirements of high sensitivity, low background dark matter detection experiments. The concentration of krypton (Kr) in a commercial xenon product can be decreased from 10−9 to 10−12 mol/mol based on the theoretical design and simulation. The experimental measurements showed that the concentration of krypton was decreased to 10−11 mol/mol with 99% xenon collection efficiency at maximum flow rate of 5 kg/h. Over 500 kg of xenon has been purified using this system, which has been used as the detection medium in project Panda X, the first dark matter detector developed in China.

Effect of photo-corrosion of Ag2CO3 on visible light photocatalytic activity of two kinds of Ag2CO3/TiO2 prepared from different precursors

Two kinds of Ag2CO3/TiO2 nanocomposite photocatalysts, Ag2CO3/P25 (P25 refers to TiO2 of Degussa Company of Germany produced by gas-phase method) and Ag2CO3/TiO2(Vo•) (Vo• refers to single-electron-trapped oxygen vacancy (abridged as SETOV)), were prepared by precipitation method with commercial P25-TiO2 and TiO2(Vo•) as the precursors. The photocatalytic activity of as-prepared Ag2CO3/P25 and Ag2CO3/TiO2(Vo•) was compared by monitoring the oxidation of propylene under visible light irradiation with pure Ag2CO3 photocatalyst as a reference. The oxidation reaction of propylene was performed in two different reaction systems, i.e., a glass reactor combined with a home-made xenon lamp (denoted as system I) and a quartz reactor combined with a commercial xenon lamp (denoted as system II), respectively. Furthermore, X-ray photoelectron spectroscopic analysis, X-ray diffraction analysis, and diffuse reflection spectrometric analysis of Ag2CO3/P25 and Ag2CO3/TiO2(Vo•) before and after visible light irradiation were conducted to investigate the effect of Ag2CO3 photo-corrosion on the activity of the two kinds of photocatalysts, and their photocatalytic mechanisms were proposed. It was found that in system I (light intensity irradiated on to-be-tested samples at λ=420nm: about 9mW/cm2), Ag2CO3/TiO2(Vo•) shows highly efficient and stable visible light activity and provides a propylene removal rate of up to 90% which remains unchanged within 4h of irradiation, while the degradation rate of propylene over Ag2CO3/P25 is reduced gradually from 35% to nearly zero within 2.5h of irradiation. In system II (light intensity at λ=420nm: about 40mW/cm2), both Ag2CO3/P25 and Ag2CO3/TiO2(Vo•) exhibit similar photocatalytic activity of up to ca. 90%. Besides, photo-corrosion of Ag2CO3 happens during photocatalytic process to afford metallic Ag, and such a photo-corrosion is originally non-conducive to the photocatalysts. Nevertheless, metallic Ag is responsible for strong surface plasmon resonance effect of Ag2CO3/P25 and desired electron capture ability of Ag2CO3/TiO2(Vo•) as well, leading to highly efficient visible light activity of Ag2CO3/P25 in system II. As to Ag2CO3/TiO2(Vo•), a large amount of SETOV induces a new sub-band between the valence band and conduction band of TiO2(Vo•), and this sub-band synergistically functions with nascent surface metallic Ag to result in highly visible light activity. Thus the present approach could provide a versatile strategy for the synthesis of novel and efficient visible light-activated photocatalysts.

Flash-lamp annealing of ZnO-layers on copper–indium–gallium–sulphide layers: A spectroscopic ellipsometry study

Polycrystalline copper–indium–(gallium)–sulphide (CI(G)Su) absorbers were analysed by spectroscopic ellipsometry (SE) with special emphasis on the optical band gap energy. Rough CI(G)Su absorber films grown by reactive magnetron sputtering were peeled off from molybdenum coated glass substrates. The smooth back side of CI(G)Su absorbers was suited for the SE analysis. Furthermore, these samples were covered with a thin zinc oxide (ZnO) layer and heat-treated with a commercial xenon flash lamp annealing system (FLA) as well as by thermal annealing in an argon atmosphere. The effect of zinc on CI(G)Su absorber films was studied by secondary ion mass spectrometry depth profiling as well as by SE analysis. The optical modelling of spectral Stokes parameters was performed by using a multilayer approach over a spectral range from 1.5 to 4.3eV. Spectral absorption coefficients were calculated in every process stage, i.e. (i) peeled samples, (ii) ZnO deposition, (iii) FLA treatment and (iv) etching of the ZnO. Special emphasis was given to the shift of the optical band gap due to the various treatments. While the SE analysis was quite sensitive to the change of optical band gaps due to a varying gallium content in the CI(G)Su absorber layers, a significant shift of the optical band gap due to increasing zinc content was not detectable.

Design and construction of a cryogenic distillation device for removal of krypton for liquid xenon dark matter detectors

Liquid xenon (Xe) is one of the commendable detecting media for the dark matter detections. However, the small content of radioactive krypton-85 ((85)Kr) always exists in the commercial xenon products. An efficient cryogenic distillation system to remove this krypton (Kr) from commercial xenon products has been specifically designed, developed, and constructed in order to meet the requirements of the dark matter experiments with high- sensitivity and low-background. The content of krypton in regular commercial xenon products can be reduced from 10(-9) to 10(-12), with 99% xenon collection efficiency at maximum flow rate of 5 kg/h (15SLPM). The purified xenon gases produced by this distillation system can be used as the detecting media in the project of Panda X, which is the first dark matter detector developed in China.

Numerical study on xenon positive column discharges of mercury-free lamp

In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells.

A cost-effective and versatile xenon gas dispenser

To modify a commercial xenon gas dispenser so that two xenon unit-dose vials could be combined with a modified dispenser to deliver a recommended dose. To maintain the same operating mechanism, changes were made only to the vial shield and the needle port of the original gas dispenser. The modified gas dispenser consisted of two puncture needles and two vial holders shielded with the same thickness of lead as the commercial dispenser. Our evaluation showed that the modified gas dispenser operated the same way as the commercial unit, and the average 133Xe residual activity in either one or two xenon unit-dose vials of the modified gas dispenser was not significantly different from that in one vial of the commercial xenon gas dispenser. The modified xenon gas dispenser allows the stock of xenon gas vials to be managed cost-effectively. The modified unit can be used to dispense two low-activity xenon gas vials to deliver a standard dose to a patient. Also, the modified gas dispenser can be used to combine different amounts of xenon activity in two unit-dose vials in order to customize the dose delivered to patients with special needs (e.g., obese patients). Our modified device can also function as a single-dose dispenser by placing an empty vial alongside the unit-dose vial of radioactive xenon gas.

Technique for stroboscopic analysis of the tip motion of ultrasonic surgical devices

Ultrasonic instruments used in surgical applications (e.g., ophthalmology, neurosurgery, dentistry) have vibrating tips driven at frequencies from 20 to 60 kHz, and maximum peak-to-peak tip excursions ranging up to several hundred micrometers. To study the tip motion, a stroboscopic system has been developed consisting of a digitally generated delay that automatically steps through the excursion cycle, a commercial xenon flashlamp strobe, and optics that permit video display and recording. The digital delay uses two 8-bit, synchronous binary counters with asychronously loaded data inputs. These counters are configured so as to produce a pulse train for strobe triggering that has successive pulse periods that differ by one clock cycle. Of the two possible sources for image blur, the finite light pulse duration and strobe jitter, the former is more significant because light pulse durations of less than 1 μs are difficult to obtain with xenon flashlamps. Image magnifications of up 550× are possible with the technique, with a tip displacement resolution of approximately 5 μm. The technique has been used to visualize the tip motion of an ophthalmic phacoemulsifier operating at 28 kHz and having a maximum tip excursion of 100 μm.

Color schlieren photographic system

Color schlieren has come to mean, not only schlieren images in color, but images where the color can be quantitatively related to the directions of the density gradients in the flow field. A system essentially consisting of three conventional schlieren systems using knife-edge cutoffs, rotated 120 deg with respect to each other, where the light source for each system is in one of the three primary colors is described. It is shown that combinations of these colors (creating a unique color) on the schlieren image resulting from the angled cutoff configuration is a function of the direction of the density gradient only. A variety of relatively inexpensive methods of producing the primary color beams are tested and it is shown that a color beamsplitter using dichroic filters with three standard commercial xenon flash tubes is suitable to obtain good results for high-speed applications. For steady flow applications, a single incandescent lamp used in conjunction with color filters and a diffusing screen is shown to be adequate for qualitative results.

Fourier Transform Fluorescence Excitation Spectroscopy in a Supersonic Jet

Laser analytical methods are usually preferred for supersonic jet spectroscopy since a high photon flux across a narrow spectral region is required for sensitive detection. Lamp sources have been used for fluorescence excitation, but their performance has been poor due to low photon fluxes. The major problems associated with lamp excitation lie not in the radiant output of the lamp but in the ability to transfer the radiation to the experiment. For example, commercial 1000-W xenon arc lamp systems can deliver up to 40 mW/nm in a

Device for controlled intensification of the light output of xenon flash tubes

A circuit has been designed for the operation of commercial xenon tubes with flexible application to stroboscopic micrography in biological researches. This operation system enables intensification of the light output for successive flashes in a short time for high-resolution photography.

Performance of an array of plasma pinches as a new optical pumping source for dye lasers

A new optical pumping source consisting of an array of plasma pinches in the hypocycloidal-pinch geometry is employed to pump a variety of dye lasers. A dye cuvette is inserted along the symmetry axis of the plasma device such that it may be surrounded by the plasma pinch. The light from the plasma pinch is very intense and rich in ultraviolet, which makes it an attractive optical pumping source for dye lasers, particularly in the blue-green spectral region. Control of the plasma fluorescence is achieved by the choice of gas, its fill pressure, and the capacitor bank voltage and its stored energy. The rise time of this ‘‘plasma flashlamp’’ depends mainly on the gas species and the fill pressure. Output energy of ∼2 mJ per cm3 of lasing medium, or 2 kW/cm3 for a 1-μs laser pulse, is obtained from rhodamine 6G, coumarin 480, LD 490, and coumarin 504 dyes. That both the coumarin 480 and rhodamine 6G lasers have the comparable output power is a direct proof that the present optical pumping source is more efficient than the commercial xenon flashlamps in pumping lasers in the blue-green spectral region.

Factors affecting the trapping performance of xenon holdup--filters in nuclear medicine applications.

Activated charcoal traps are used in nuclear medicine departments to capture exhaled radioactive xenon gas. In the present study, the trapping performance of charcoal was investigated for different physical qualities in experimental and clinical situations. Various factors affecting the trapping capacity are identified, such as the charcoal mass, moisture and carbon-dioxide concentrations in the sweep gas, gas-flow rate through the trap, and temperature. Improper drying of the exhaled air prior to passage through the charcoal bed appears to be a critical factor, leading to a much earlier breakthrough of xenon. Commercial xenon traps intended for ambient temperature operation were found to be useful only for a limited number of patients due to an early breakthrough point. By refrigerating the trap, however, a much larger capacity was achieved. If correctly managed, xenon traps constitute a useful alternative for isolating radioactive xenon wastes in clinical and experimental applications.

A 200 W average power, narrow bandwidth, tunable waveguide dye laser

A planar waveguide dye laser, driven by commercial xenon flashlamps with an average power output of 200 W at 50 pulse per second (pps) is described. Due to the planar structure, a narrow bandwidth operation down to 10 GHz has been obtained with a single grating arranged at grazing incidence. With this configuration, high overall efficiency up to 0.6 percent has been obtained, partially due to energy conversion of the broad-band emission spectrum of the flash-lamps by circulating an appropriate dye solution between flashlamps and reflectors.

A reliable high average power dye laser

A pulsed dye laser using commercial xenon flashlamps in a novel pump geometry and using thyristors for switching having an average laser output power capability of 100 W is described.

The gas amplification factor in xenon filled proportional counters

The gas amplification factor in a variety of commercial xenon filled proportional counters has been found to obey equally well both the Diethorn equation and the Zastawny equation over the range of variables studied. Constants appropriate to each equation have been determined for both Xe-5%CO 2 and Xe-10%CH 4 fill gases.