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A coupled optical-electrical-thermal modeling has been developed to investigate the heat generation and dissipation in Cu2ZnSn4SxSe4−x thin film solar cells. Five heat generation factors: Thermalization, Joule heat, Peltier heat, Surface Recombination heat, and non-radiative recombination heat (Shockley-Read-Hall and Auger) as well as two heat dissipation factors convective and radiative cooling were calculated and displayed in 2 and 3 dimensional maps. Thermalization is the dominant heat generation factor in the cell independent of the voltage. The non-radiative recombination heat and Joule heat depend on voltage. Apart from these bulk heating factors, the surface recombination heat and Peltier heat were also investigated. The surface recombination heat is higher at open-circuited voltage (V=Voc) compared to at V = 0 while the Peltier heat is zero at V=Voc which can be explained by looking at the energy band diagrams at these voltages. The total heat generation has a small gradient across the cell thickness (

The pathway of activationless proton transfer induced by an electron-transfer reaction is studied theoretically. Long-range electron transfer produces highly nonequilibrium medium polarization that can drive proton transfer through an activationless transition during the process of thermalization, dynamically altering the screening of the electron-proton Coulomb interaction by the medium. The cross electron-proton reorganization energy is the main energy parameter of the theory, which exceeds in magnitude the proton-transfer reorganization energy roughly by the ratio of the electron-transfer to proton-transfer distance. This parameter, which can be either positive or negative, is related to the difference in pKa values in two electron-transfer states. The relaxation time of the medium is on the (sub)picosecond time scale, which establishes the characteristic time for activationless proton transfer. Microscopic calculations predict substantial retardation of the collective relaxation dynamics compared to the continuum estimates due to the phenomenology analogous to de Gennes narrowing. Nonequilibrium medium configuration promoting proton transfer can be induced by either thermal or photoinduced charge transfer.

We study, by optical spectroscopy, the properties of high-current electric arcs that form between opening Cu contacts. The presence of a current that increases linearly with a rate of about 14 kA/ms leads to the separation of the contacts and to the formation of a bridge of molten metal that eventually ruptures. We show that after the molten bridge rupture, it takes about 40 $\mu \text{s}$ for the initial arc to be at local thermal equilibrium. This long thermalization time suggests that the plasma density during that time range is low, which we confirm using a simple modeling of the energy transfer between electrons and heavy particles. We explain these low densities by the fact that the molten bridge rupture leads to the formation of a shock wave. The initial dense plasma rapidly expands and a region with a pressure below the background pressure forms between the two contacts, leading to low plasma densities and long thermalization times.

The trend toward miniaturization of electronic devices has increased the interest in nano scale heat transport, particularly, in laser-excited solids where electron–electron thermalization and elec...

Photoluminescent materials are advanced cutting-edge heat-rejecting materials capable of reemitting a part of the absorbed light through radiative/non-thermal recombination of excited electrons to their ground energy state. Photoluminescent materials have recently been developed and tested as advanced non-white heat-rejecting materials for urban heat mitigation application. Photoluminescent materials has shown promising cooling potential for urban heat mitigation application, but further developments should be made to achieve optimal photoluminescence cooling potential. In this paper, an advanced mathematical model is developed to explore the most efficient methods to enhance the photoluminescence cooling potential through estimation of contribution of non-radiative mechanisms. The non-radiative recombination mechanisms include: (1) Transmission loss and (2) Thermal losses including thermalization, quenching, and Stokes shift. The results on transmission and thermal loss mechanisms could be used for systems solely relying on photoluminescence cooling, while the thermal loss estimations can be helpful to minimize the non-radiative losses of both integrated photoluminescent-near infrared (NIR) reflective and stand-alone photoluminescent systems. As per our results, the transmission loss is higher than thermal loss in photoluminescent materials with an absorption edge wavelength (λAE) shorter than 794 nm and quantum yield (QY) of 50%. Our predictions show that thermalization loss overtakes quenching in photoluminescent materials with λAE longer than 834 nm and QY of 50%. The results also show that thermalization, quenching, and Stokes shift constitute around 56.8%, 35%, and 8.2% of the overall thermal loss. Results of this research can be used as a guide for the future research to enhance the photoluminescence cooling potential for urban heat mitigation application.

The eigenstate thermalization hypothesis (ETH) is discussed. We note that one common formulation of the ETH does not necessarily imply thermalization of an observable of an isolated many-body quantum system. We show that to get thermalization, one has to postulate the canonical or microcanonical distribution in the ETH ansatz. More generally, any other average can be postulated in the generalized ETH ansatz, which leads to a corresponding equilibration condition.

Here, we present a short review of ideas, methods and results for understanding the evolution of an excited mesoscopic system of strongly interacting constituents. We discuss the process of thermalization with its characteristic time dependence different from what is known in classical mechanics, the resulting state of quantum chaos, enhancement of sensitivity to weak perturbations including violation of fundamental symmetries in nuclei, problem of the level density, and effects of continuum and superradiance.

The theory of forbidden rotational transitions is reviewed and spontaneous emission rates and lifetimes of metastable levels of NH3, H3O+, H3+, and CH3CN are calculated. Rotational levels are classified into stable, metastable, and unstable levels. The importance of the forbidden rotational transitions in the thermalization of interstellar molecules is discussed.

In our result about dynamical thermalization, the proof of the upper bound on the time average of the distance between the local evolved state

A deep understanding of hot carrier (HC) dynamics is important to improve the performance of optoelectronic devices by reducing the thermalization losses. Here, we investigate the hot hole cooling ...

Hot electrons in metal nanoparticles thermalize with the lattice via electron–phonon coupling. Size dependency is controversially discussed in literature. Here we investigate poly- and monocrystall...

It is found that the thermalization of triplet spin-flip magneto-excitons in a quantum Hall dielectric is an unprecedentedly long process for translation-invariant nonequilibrium electronic systems. It is shown that a magneto-fermionic condensate, a state characterized by the ability to rapidly transfer spin over macroscopic distances, is formed by spin-flip excitons with generalized momenta on the order of the reciprocal magnetic length.

Understanding and classifying nonequilibrium many-body phenomena, analogous to the classification of equilibrium states of matter into universality classes, is an outstanding problem in physics. Any many-body system, from stellar matter to financial markets, can be out of equilibrium in a myriad of ways; since many are also difficult to experiment on, it is a major goal to establish universal principles that apply to different phenomena and physical systems. At the heart of the classification of equilibrium states is the universality seen in the self-similar spatial scaling of systems close to phase transitions. Recent theoretical work, and first experimental evidence, suggest that isolated many-body systems far from equilibrium generically exhibit dynamic (spatiotemporal) self-similar scaling, akin to turbulent cascades and the Family-Vicsek scaling in classical surface growth. Here we observe bidirectional dynamic scaling in an isolated quench-cooled atomic Bose gas; as the gas thermalises and undergoes Bose-Einstein condensation, it shows self-similar net flows of particles towards the infrared (smaller momenta) and energy towards the ultraviolet (smaller lengthscales). For both infrared (IR) and ultraviolet (UV) dynamics we find that the scaling exponents are independent of the strength of the interparticle interactions that drive the thermalisation., 5 pages, 4 figures

A concise summary of out-of-equilibrium dark matter production during post-inflationary reheating is presented. We show that the dark matter relic abundance is in general sensitive to the thermalization rate of the inflaton decay products, and the evolution of the temperature of the subsequently thermalized radiation. We discuss how smoking-gun signals, such as monochromatic neutrinos or gamma-ray lines, or Lyman-$\alpha$ data, can help constrain out-of-equilibrium DM models., Comment: 6 pages, 4 figures. Contribution to the IWARA 2020 conference proceedings

The lifetimes of hot carriers have been predicted to be prolonged in small nanocrystals with an inter-level spacing larger than phonon energy. Nevertheless, whether such a phonon bottleneck is present in perovskite semiconductor nanocrystals remains highly controversial. Here we report compelling evidence of a phonon bottleneck in CsPbI3 nanocrystals with marked size-dependent relaxation of hot carriers by using broadband two-dimensional electronic spectroscopy (2DES). By combining high resolutions in both the time (

It is shown that there are three characteristic time scales for the establishment of thermodynamic equilibrium: the time for the thermalization of the system; the time for establishing a uniform temperature in the system after contact with the thermostat; and, finally, the time for establishing full ergodicity in the system. The first time is determined by particle collisions (in fluids) or multiphonon processes (in condensed media) and lies in the range from tens of picoseconds (in dense fluids) to microseconds (in pure crystals at low temperatures). The second time is determined by the thermal diffusivity and the size of the system and, for millimeter-sized samples, lasts for seconds. The third time is determined by the particle diffusion rates and can vary from hundreds of picoseconds (in gases and liquids) to astronomical times (in solids at low temperatures). The concept of ergodicity as applied to crystals and glasses is discussed.

Collective behavior strongly influences the charging dynamics of quantum batteries (QBs). Here, we study the impact of nonlocal correlations on the energy stored in a system of $N$ QBs. A unitary charging protocol based on a Sachdev-Ye-Kitaev (SYK) quench Hamiltonian is thus introduced and analyzed. SYK models describe strongly interacting systems with nonlocal correlations and fast thermalization properties. Here, we demonstrate that, once charged, the average energy stored in the QB is very stable, realizing an ultraprecise charging protocol. By studying fluctuations of the average energy stored, we show that temporal fluctuations are strongly suppressed by the presence of nonlocal correlations at all time scales. A comparison with other paradigmatic examples of many-body QBs shows that this is linked to the collective dynamics of the SYK model and its high level of entanglement. We argue that such feature relies on the fast scrambling property of the SYK Hamiltonian, and on its fast thermalization properties, promoting this as an ideal model for the ultimate temporal stability of a generic QB. Finally, we show that the temporal evolution of the ergotropy, a quantity that characterizes the amount of extractable work from a QB, can be a useful probe to infer the thermalization properties of a many-body quantum system., 13 pages, 11 figures; v2: references added; a new section discussing the role of quantum chaos added; version to appear on JHEP

A simplified model of thermally stimulated luminescence (TSL) and optically stimulated luminescence (OSL) kinetics is considered for the case of impeded carrier transport. A response function is obtained for the OSL with transport barrier, being of special interest for the extreme case of saturation mode (when the optical term in the model exceeds all other terms). In this case, the maximum of the response function does not depend on the stimulating light intensity but is proportional to the recombination rate, which in turn, depends on the transport barrier and temperature. A high barrier makes the OSL ineffective, whereas the elevated temperatures can increase OSL response for moderate barriers. If carriers released by light are transferred deeper to the respective energy band, they can overcome the transport barrier during their thermalization, which decreases the temperature required for OSL.

Over the past decade, there has been remarkable progress in our understanding of equilibration, thermalization and prethermalization, due in large part to experimental breakthroughs in ultracold atomic gases. These advances have made it possible to investigate how isolated quantum systems thermalize and why certain special many-body states do not. An overview on recent theoretical and experimental developments is given. The past decade has witnessed remarkable progress in our understanding of equilibration, thermalization and prethermalization, due in large part to experimental breakthroughs in ultracold atomic gases. This Review discusses theoretical and experimental advances on these topics and the challenges ahead.

We consider a disordered Hubbard model, and show that, at sufficiently weak disorder, a single spin-down mobile impurity can thermalize an extensive initially localized system of spin-up particles. Thermalization is enabled by resonant processes which involve correlated hops of the impurity and localized particles. This effect indicates that certain localized insulators behave as "supercooled" systems, with mobile impurities acting as ergodic seeds. We provide analytical estimates, supported by numerical exact diagonalization (ED), showing how the critical disorder strength for such mechanism depends on the particle density of the localized system. In the $U\rightarrow\infty$ limit, doublons are stable excitations, and they can thermalize mesoscopic systems by a similar mechanism. The emergence of an additional conservation law leads to an eventual localization of doublons. Our predictions apply to fermionic and bosonic systems and are readily accessible in ongoing experiments simulating synthetic quantum lattices with tunable disorder., Comment: 5 pages + supplementary material (8 pages)

There is an emerging consensus that large amounts of gas do not shock heat in the circumgalactic medium (CGM) of massive galaxies, but instead pierce deep into haloes from the cosmic web via filaments. To better resolve this process numerically, we have developed a novel `shock refinement' scheme within the moving mesh code AREPO that adaptively improves resolution around shocks on-the-fly in galaxy formation simulations. We apply this to a massive $\sim10^{12}$ M$_\odot$ halo at $z=6$ using the successful FABLE model, increasing the mass resolution by a factor of 512. With better refinement there are significantly more dense, metal-poor and fast-moving filaments and clumps flowing into the halo, leading to a more multiphase CGM. We find a $\sim50$ per cent boost in cool-dense gas mass and a 25 per cent increase in inflowing mass flux. Better resolved accretion shocks cause turbulence to increase dramatically, leading to a doubling in the halo's non-thermal pressure support. Despite much higher thermalisation at shocks with higher resolution, increased cooling rates suppress the thermal energy of the halo. In contrast, the faster and denser filaments cause a significant jump in the bulk kinetic energy of cool-dense gas, while in the hot phase turbulent energy increases by up to $\sim150$ per cent. Moreover, HI covering fractions within the CGM increase by up to 60 per cent. Consequently star formation is spread more widely and we predict a population of metal-poor stars forming within primordial filaments that deep JWST observations may be able to probe., 21 pages, 14 figures. Accepted for publication in MNRAS after minor revisions

Charge carrier multiplication via singlet fission into two triplet states has the potential to increase efficiencies of photovoltaics by one-third due to the reduction of thermalization losses. In the present work, we investigate tetraazaperopyrenes, a class of N-heteropolycyles, as suitable singlet fission candidates. Using a combined experimental and theoretical approach, fundamentally different mechanisms for triplet formation in solution and thin film are identified. In solution, an ultrafast intersystem crossing process is observed, which is accelerated for heavier halide substituents not only due to enhanced spin-orbit coupling but also due to the energy tuning between the S1 and T2 states. In thin films, a correlated triplet pair is formed coherently upon photoexcitation. Subsequently, an excimer formation is observed, which competes with the electronic decorrelation of the triplet pair. The comparison with peropyrene shows that aza-substitutions within the aromatic core can be a powerful strategy for tuning the energy levels of the states important to singlet fission.

In many quantum quench experiments involving cold atom systems the post-quench system can be described by a quantum field theory of free scalars or fermions, typically in a box or in an external potential. We work with free scalars in arbitrary dimensions generalizing the techniques employed in our earlier work \cite{Mandal:2015kxi} in 1+1 dimensions. In this paper, we generalize to $d$ spatial dimensions for arbitrary $d$. The system is considered in a box much larger than any other scale of interest. We start with the ground state, or a squeezed state, with a high mass and suddenly quench the system to zero mass ("critical quench"). We explicitly compute time-dependence of local correlators and show that at long times they are described by a generalized Gibbs ensemble (GGE), which, in special cases, reduce to a thermal (Gibbs) ensemble. The equilibration of {\it local} correlators can be regarded as `subsystem thermalization' which we simply call 'thermalization' here (the notion of thermalization here also includes equlibration to GGE). The rate of approach to equilibrium is exponential or power law depending on whether $d$ is odd or even respectively. As in 1+1 dimensions, details of the quench protocol affect the long time behaviour; this underlines the importance of irrelevant operators at IR in non-equilibrium situations. We also discuss quenches from a high mass to a lower non-zero mass, and find that in this case the approach to equilibrium is given by a power law in time, for all spatial dimensions $d$, even or odd., 27+12 pages, 6 figures

Needle-like metallic particles have been suggested to explain a wide variety of astrophysical phenomena, ranging from the mid-infrared interstellar extinction to the thermalization of starlight to generate the cosmic microwave background. These suggestions rely on the amplitude and the wavelength dependence of the absorption cross sections of metallic needles. On the absence of an exact solution to the absorption properties of metallic needles, their absorption cross sections are often derived from the antenna approximation. However, it is shown here that the antenna approximation is not an appropriate representation since it violates the Kramers-Kronig relation. Stimulated by the recent discovery of iron whiskers in asteroid Itokawa and graphite whiskers in carbonaceous chondrites, we call for rigorous calculations of the absorption cross sections of metallic needle-like particles, presumably with the discrete dipole approximation. We also call for experimental studies of the formation and growth mechanisms of metallic needle-like particles as well as experimental measurements of the absorption cross sections of metallic needles of various aspect ratios over a wide wavelength range to bound theoretical calculations., 5 pages, 1 figure; accepted for publication in MNRAS

The article considers the poorly studied states of hydrogen gas (called here “quasi-resonant”) with anomalously high intensity ratios of the lines in the Balmer series, $$I({{{\text{H}}}_{\alpha }}){\text{/}}I({{{\text{H}}}_{\beta }})$$ . It is shown that such states arise in the case of large optical thicknesses of the emitting gas occurring at the frequencies of the Balmer lines, when the gas tends to a thermalization state. The influence on the formation of such states of basic model parameters as temperature, atomic density, and the characteristic size of the emitting region, as well as the presence of external radiation, is studied on simple models. It is shown that quasi-resonant states can exist in the magnetospheres of T Tauri stars at moderate accretion rates.

The thermal neutron scattering cross-section of a solid depends on the energy (or wavelength) of the incident neutrons. Devising a method to calculate the energy dependence from first principles, without the approximations built in the scattering theory, has been a major undertaking in nuclear engineering. Here, we demonstrate such a calculation method using the program OCLIMAX. Our approach eliminates various approximations and limitations involved in a regular calculation with the LEAPR module of NJOY code, and the results are compared with available experimental and theoretical data. It is also demonstrated how additional insight can be obtained from the calculated full dynamical structure factor. The results reported here show the great potential and excellent platform provided by OCLIMAX for future development in the study of neutron thermalization in solid materials for different applications.

It is showed that one common formulation of ETH does not necessarily imply thermalization (in some sense) of an observable of isolated many body quantum system. To get such thermalization one has to postulate it in the ETH-ansatz.

Properties of plasmas that constitute the plasma sheet in the near-Earth magnetotail vary according to the solar wind conditions and location in the tail. In this case study, we present multi-spacecraft observations by Cluster that show a transition of plasma sheet from cold, dense to hot, tenuous state. The transition was associated with the passage of a spatial boundary that separates the plasma sheet into two regions with cold, dense and hot, tenuous plasmas. Ion phase space distributions show that the cold, dense ions have a Kappa distribution while the hot, tenuous ions have a Maxwellian distribution, implying that they have different origins or are produced by different thermalization processes. The transition boundary separated the plasma sheet in the dawn-dusk direction, and slowly moved toward the dawn flank. The hot, tenuous plasmas filled the central region while the cold, dense plasmas filled the outer region. The hot, tenuous plasmas were moving toward the Earth, pushing the cold, dense plasmas toward the flank. Different types of dynamical processes can be generated in each region, which can affect the development of geomagnetic activities.

Bosonic condensates offer exciting prospects for studies of non-equilibrium quantum dynamics. Understanding the dynamics is particularly challenging in the sub-picosecond timescales typical for room temperature luminous driven-dissipative condensates. Here we combine a lattice of plasmonic nanoparticles with dye molecule solution at the strong coupling regime, and pump the molecules optically. The emitted light reveals three distinct regimes: one-dimensional lasing, incomplete stimulated thermalization, and two-dimensional multimode condensation. The condensate is achieved by matching the thermalization rate with the lattice size and occurs only for pump pulse durations below a critical value. Our results give access to control and monitoring of thermalization processes and condensate formation at sub-picosecond timescale., Comment: Revised version

The cold source field-effect transistor (CSFET), enabled by novel source engineering, is a promising alternative to achieve sub-60 mV/dec steep-slope switching. For the first time, we develop an industry-standard TCAD approach for the CSFET with an effective cold carrier density of states (DOS) model which captures the underlying physics of DOS engineering, cold carrier injection, and thermalization in the device. The simulation scheme uses nonequilibrium Green’s function (NEGF) simulation for calibration. The effects of source engineering, rethermalization, and channel tunneling are extensively investigated on a Si-based double-gate CSFET. Its merits are highlighted by comparison with a conventional MOSFET under various temperatures, thicknesses, and gate lengths, showing improved ${I} _{ {\mathrm{\scriptscriptstyle ON}}}/{I} _{ {\mathrm{\scriptscriptstyle OFF}}}$ in ultrascaled MOSFET.

Lead halide perovskites (LHPs) exhibit large spin-orbit coupling (SOC), leading to only twofold-degenerate valence and conduction bands and therefore allowing for efficient optical orientation. This makes them ideal materials to study charge carrier spins. With this study we elucidate the spin dynamics of photoexcited charge carriers and the underlying spin relaxation mechanisms in CsPbI3 nanocrystals by employing time-resolved differential transmission spectroscopy (DTS). We find that the photoinduced spin polarization significantly diminishes during thermalization and cooling toward the energetically favorable band edge. Temperature-dependent DTS reveals a decay in spin polarization that is more than 1 order of magnitude faster at room temperature (3 ps) than at cryogenic temperatures (32 ps). We propose that spin relaxation of free charge carriers in large-SOC materials like LHPs occurs as a result of carrier-phonon scattering, as described by the Elliott-Yafet mechanism.

OH airglow is an important nocturnal emission of the Earth's mesopause region. As it is chemiluminescent radiation in a thin medium, the population distribution over the various roto-vibrational OH energy levels of the electronic ground state is not in local thermodynamic equilibrium (LTE). In order to better understand these non-LTE effects, we studied hundreds of OH lines in a high-quality mean spectrum based on observations with the high-resolution Ultraviolet and Visual Echelle Spectrograph at Cerro Paranal in Chile. Our derived populations cover vibrational levels between v=3 and 9, rotational levels up to N=24, and individual Λ-doublet components when resolved. As the reliability of these results critically depends on the Einstein-A coefficients used, we tested six different sets and found clear systematic errors in all of them, especially for Q-branch lines and individual Λ-doublet components. In order to minimise the deviations in the populations for the same upper level, we used the most promising coefficients from Brooke et al. (2016) and further improved them with an empirical correction approach. The resulting rotational level populations show a clear bimodality for each v, which is characterised by a probably fully thermalised cold component and a hot population where the rotational temperature increases between v=9 and 4 from about 700 to about 7000 K, and the corresponding contribution to the total population at the lowest N decreases by an order of magnitude. The presence of the hot populations causes non-LTE contributions to rotational temperatures at low N, which can be estimated quite robustly based on the two-temperature model. The bimodality is also clearly indicated by the dependence of the populations on changes in the effective emission height of the OH emission layer. The degree of thermalisation decreases with increasing layer height due to a higher fraction of the hot component. Our high-quality population data are promising with respect to a better understanding of the OH thermalisation process.

Analytic solutions of a nonlinear boson diffusion equation account for the fast local equilibration of gluons in relativistic heavy-ion collisions using schematic initial conditions. The solutions describe the time-dependent approach to the Bose-Einstein equilibrium distribution with a local equilibration time of τeq ≈ 0.1 fm/c and central temperatures of the order of 500 – 600 MeV in the initial stages of Pb-Pb collisions at energies reached at the Large Hadron Collider (LHC).

Nowadays, the interaction between phonon and magnon subsystems of a magnetic medium is a hot topic of research. The complexity of phonon and magnon spectra, the existence of both bulk and surface modes, the quantization effects, and the dependence of magnon properties on applied magnetic field, make this field very complex and intriguing. Moreover, the recent advances in the fields of spin caloritronics and magnon spintronics as well as the observation of the spin Seebeck effect in magnetic insulators points on the crucial role of magnons in spin-caloric transport processes. In this review, we collect the variety of different studies in which magnon-phonon interaction play important role. The scope of the paper covers the wide range of phenomena starting from the interaction of the coherent magnons with surface acoustic wave and finishing with the formation of magnon supercurrents in the thermal gradients.

We investigate nonequilibrium steady states in an isolated system of few ultracold cesium atoms (Cs). Numerically and experimentally, we study the dynamics and fluctuations of the extracted position distributions and find the formation of nonthermal steady states for absent interactions. Atomic collisions in the s-wave regime, however, ensue thermalization of the few-particle system. We present numerical simulations of the microscopic equations of motion with a simple representation of the s-wave scattering events. Based on these simulations, a parameter range is identified, where the interaction between few atoms is sufficiently strong to thermalize the nonequilibrium steady state on experimentally accessible time scales, which can be traced by monitoring the atomic position distribution. Furthermore, the total energy distribution, which is also accessible experimentally, is found to be a powerful tool to observe the emergence of a thermal state. Our work provides a pathway for future experiments investigating the effect interactions in few-particle systems and underlines the role of fluctuations in investigating few-particle systems.

Spectroscopy of the hydroxyl (OH) airglow has been a commonly used way to remotely sense temperatures in the mesopause region for many decades. This technique relies on the OH rotational state populations to be thermalized through collisions with the surrounding gas into a Boltzmann distribution characterized by the local temperature. However, deviations of the rotational populations from a Boltzmann distribution characterized by a single temperature have been observed and attributed to an incomplete thermalization of the OH from its initial, non-thermodynamic equilibrium distribution. Here we address an additional cause for the apparent amount of excess population in the higher rotational levels of the OH airglow brought about by integrating these OH emissions through vertical gradients in the atmospheric temperature. We find that up to 40% of the apparent excess population, currently attributed to incomplete thermalization, can be due to the vertical temperature gradients created by waves. Additionally, we find that the populations of the different upper vibrational levels are affected differently. These effects need to be taken into account in order to assess the true extent of non-thermodynamic-equilibrium effects on the OH rotational populations. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.

The NSCL has successfully used linear gas stopping cells for more than a decade to slow down near-relativistic projectile fragments to energies of tens of keV; first for experiments at low energy and later for reacceleration to Coulomb-barrier energies. In order to stop and rapidly extract light and medium-mass fast ions, which are difficult to efficiently thermalize in linear gas cells, a gas-filled, reverse cyclotron has been constructed. The device uses a cyclotron-type magnet and helium gas in a liquid-nitrogen (LN) cooled stopping chamber to confine and slow down the injected beam. The stopped ions are transported to the center of the magnet by an RF-carpet system, extracted axially through the bore with an ion conveyor and accelerated to For magnet commissioning and low-energy ion tests, the cyclotron gas stopper was constructed in a location that did not allow connection to the NSCL high-energy beamlines. However, all other components have been installed for the device. Efficient ion transport has been demonstrated with ions from a movable alkali source with the magnet energized. An experimental vault is being prepared to allow the connection of the cyclotron gas stopper to the NSCL beamline. The design for a dedicated momentum-compression beam line, similar to the ones feeding the existing linear gas cells [1] , [2] , is complete and the components are under construction. Offline tests have ended and moving the cyclotron stopper to its destination has begun.

Ratiometric optical thermometry is one of the most promising techniques for contactless temperature sensing. However, despite the efforts devoted in the last decades, the development of nanothermometers characterized by high reliability along with suitable sensitivity (Sr > 1% K−1) and thermal resolution (δT < 0.5 K) in the physiological temperature range is still a critical challenge in the biological field. Here, we propose uniform Yb,Tm co-doped crystalline Bi2SiO5@SiO2 hollow upconverting nanoparticles as red-NIR emitting nanophosphors for ratiometric optical thermometry. The synthetic procedure leads to double-layered Bi2SiO5:Yb,Tm@SiO2 hollow nanoparticles. The thermometric performances are investigated in a wide temperature range (80–800 K) demonstrating the reliability of the thermometer based on the emission ratio between the 1G4 → 3F4 (∼650 nm) and 3F2,3 → 3H6 (∼700 nm) transitions. Despite the impossibility to be in thermal equilibrium due to the large energy gap between 1G4 and 3F2,3 excited states, their relative populations are demonstrated to follow the Boltzmann distribution, reflecting, through the upconversion processes, the thermalization between the 3F2,3 and 3H4 excited states. Consequently, the system features high thermal sensitivity (Sr = 1.95% K−1 at 300 K) and excellent thermal resolution (0.28 K at 300 K) for a highly reliable system following the Boltzmann-distribution. In addition, the superior performances of the investigated system in comparison with other NIR-to-NIR thermometers such as Nd3+-based ones and the biocompatibility of the NPs prove its potential in the physiological temperature range.

Liquid water being the major constituent of the human body, is of fundamental importance in radiobiological research. Hence, the knowledge of electron-water interaction physics and particularly the secondary electron yield is essential. However, to date, only very little is known experimentally on the low energy electron interaction with liquid water because of certain practical limitations. The purpose of this study was to gain some useful information about electron emission from water using a Monte Carlo (MC) simulation technique that can numerically model electron transport trajectories in water.In this study, we have performed MC simulations of electron emission from liquid water in the primary energy range of 50 eV-30 keV by using two different codes, i.e., a classical trajectory MC (CMC) code developed in our laboratory and the Geant4-DNA (G4DNA) code. The calculated secondary electron yield and electron backscattering coefficient are compared with experimental results wherever applicable to verify the validity of physical models for the electron-water interaction.The secondary electron yield vs. primary energy curves calculated using the two codes present the same generic curve shape as that of metals but in rather different absolute values. G4DNA underestimates the secondary electron yield due to the application of one step thermalization model by setting a cutoff energy at 10 eV so that the low energy losses due to phonon excitations are omitted. Our CMC code, using a full energy loss spectrum to model electron inelastic scattering, allows the simulation of individual phonon scattering events for very low energy losses down to 10 meV, which then enables the calculated secondary electron yields much closer to the experimental data and also gives quite reasonable energy distribution curve of secondary electrons.It is concluded that full dielectric function data at low energy loss values below 10 eV are recommended for modeling of low energy electrons in liquid water.

We employ hydrodynamical simulations to investigate the underlying mechanism responsible for the low levels of gas and dust in globular clusters. Our models examine the competing effects of energy and mass supply from the various components of the evolved stellar population for globular clusters 47 Tucanae, M15, NGC 6440, and NGC 6752. Ignoring all other gas evacuation processes, we find that the energy output from the stars that have recently turned off the main sequence are capable of effectively clearing the evolved stellar ejecta and producing intracluster gas densities consistent with current observational constraints. This result distinguishes a viable gas and dust evacuation mechanism that is ubiquitous in globular clusters. In addition, we extend our analysis to probe the efficiency of pulsar wind feedback in globular clusters. The detection of intracluster ionized gas in 47~Tucanae allows us to place particularly strict limits on pulsar wind thermalization efficiency, which must be extremely low in the cluster's core in order to be in accordance with the observed density constraints., Comment: 13 pages, 9 figures, published to MNRAS