Is SU(3) gauge theory with 13 massless flavors conformal?

We use lattice simulations to study SU(3) gauge theory with 13 massless fermions in the fundamental representation. We present evidence that the theory is conformal with a non-zero infrared fixed point in the gauge coupling. We use a newly-developed technique to calculate the mass anomalous dimension at the fixed point via step-scaling of the mode number, allowing us to take the continuum limit and compare to perturbative predictions. We comment on the relevance of these findings to the extended search for the conformal window in the fundamental representation and in particular 12 massless flavors.Comment: 7 pages, 7 figures; Proceedings for the 36th Annual International Symposium on Lattice Field Theory, 22-28 July 2018, Michigan State University, East Lansing, Michigan, US

Fate of a recent conformal fixed point and β-function in the SU(3) BSM gauge theory with ten massless flavors

SU(3) gauge theory with $N_f$ fermions in the fundamental representation serves as a theoretical testing ground for possible infrared conformal behavior, which could play a role in BSM composite Higgs models. We use lattice simulations to study the 10-flavor model, for which it has been claimed there is an infrared fixed point in the gauge coupling $\beta$-function. Our results suggest the opposite conclusion, namely we find no $\beta$-function fixed point in the explored range, with qualitative agreement with the 5-loop $\overline{MS}$ prediction. We comment on the inconsistency between our findings and other studies.Comment: 7 pages, 6 figures; Proceedings for the 36th Annual International Symposium on Lattice Field Theory, 22-28 July 2018, Michigan State University, East Lansing, Michigan, US

Sensitivity of Micromachined Joule-Thomson Cooler to Clogging Due to Moisture

A major issue in long-term operation of micromachined Joule-Thomson coolers is the clogging of the microchannels and/or the restriction due to the deposition of water molecules present in the working fluid. In this study, we present the performance of a microcooler operated with nitrogen gas with different moisture levels. Relatively low-purity nitrogen gas (5.0) is supplied from a gas bottle and led through a filter to control the moisture level. The filter consists of a tube-in-tube counter flow heat exchanger (CFHX) and a heat exchanger that is stabilized at a certain temperature by using a Stirling cooler. The set-point temperature determines the moisture level at the exit of the heat exchanger. It is found that the moisture level has influence on the mass-flow rate during the cool down. Once the microcooler reaches the set cold-end temperature, the main deposition area shifts into the CFHX and the moisture level at the restriction is almost independent on the inlet moisture level of the microcooler. The moisture level at the restriction increases with the increasing cold-end temperature when the cold-end temperature is lower than the saturation temperature of the water in the nitrogen gas. Higher cold-end temperature results in higher clogging rate

Vibration-free Cooler for the METIS Instrument Using Sorption Compressors

METIS is the “Mid-infrared ELT Imager and Spectrograph” for the European Extremely Large Telescope (E-ELT) that will cover the thermal/mid-infrared wavelength range from 3-14 micron. Starting from a pumped nitrogen line at 70K, it requires cryogenic cooling of detectors and optics at 40 K (1.4 W), 25 K (1.1 W), and 8 K (0.4 W). A vibration-free cooling technology for this instrument based on sorption coolers is under development at the University of Twente in collaboration with Dutch Space. We propose a sorption-based cooler with three cascaded Joule-Thomson coolers of which the sorption compressors are all heat sunk at the 70K platform. A helium-operated cooler is used to obtain the 8K level with a cooling power of 0.4 W. Here, three pre-cooling stages are used at 40K, 25K and 15K. The latter two levels are provided by a hydrogen-based cooler, whereas the 40K level is realized by a neon-based sorption cooler. Based on our space-cooler heritage, our preliminary design used sorption compressors equipped with gas-gap heat switches. These have maximum efficiency, but the gas-gap switches add significantly to the complexity of the system. Since in METIS relatively high cooling powers are required, and thus a high number of compressor cells, manufacturability is an important issue. We, therefore, developed an alternative cylindrical compressor design that uses short-pulse heating establishing a thermal wave in radial direction. This allows to omit the gas-gap heat switch. The paper discusses the adapted cell design and two METIS cooler demonstrator setups that are currently under construction

A Passive, Adaptive and Autonomous Gas Gap Heat Switch

We report on the development of a heat switch for autonomous temperature control of electronic components in a satellite. A heat switch can modulate when needed between roles of a good thermal conductor and a good thermal insulator. Electronic boxes on a satellite should be maintained within a typical optimum temperature range of 260 to 310 K. The heat sinking is usually by means of a radiator. When the operating temperature of the electronic box increases beyond 310 K, a good contact to the radiator is desired for maximum cooling. On the other hand, when the satellite is in a cold dormant state, the electronics box should be heated by the onboard batteries. In this state a weak thermal contact is desired between the electronic box and the heat sink. In the present study, we are developing a gas gap heat switch in which the sorber material is thermally anchored to the electronic box. A temperature change of the electronic box triggers the (de-)sorption of gas from the sorber material and subsequently the gas pressure in the gas gap. This paper describes the physical principles and the current status of this technology. This approach can be extended to cryogenic temperature rang

Scheme for the preparation of the multi-particle entanglement in cavity QED

Here we present a quantum electrodynamics (QED) model involving a large-detuned single-mode cavity field and $n$ identical two-level atoms. One of its applications for the preparation of the multi-particle states is analyzed. In addition to the Greenberger-Horne-Zeilinger (GHZ) state, the W class states can also be generated in this scheme. The further analysis for the experiment of the model of $n=2$ case is also presented by considering the possible three-atom collision.Comment: 5 Pages, 1 Figure. Minor change

Use of Z-pinch radiation sources for high-pressure shock wave studies

The authors are developing a new shock wave diagnostic using Z pinch sources for high-pressure equation of state (EOS) measurements. Specifically, they are employing VISAR interferometry to measure the particle velocity of shocked materials and fiber optic probes to measure the shock speed. Combination of these measurements will allow absolute EOS data with Z accelerators. This report is a progress report on the development of this new approach to EOS measurements; however, preliminary data obtained with the diagnostics are encouraging. With further development of Z pinch sources, it is envisioned that a variety of EOS and constitutive property measurements can be made. Time-resolved wave profile measurements will then provide a variety of EOS and material property data, such as isentropic EOS, initial compressive strength and shock-induced compressive strength, dynamic tensile strength, kinetics of phase transitions, and surface stability studies