Search results for "Heat Transfer"
showing 10 items of 442 documents
Ordinary muon capture studies for the matrix elements in ββ decay
2018
Precise measurement of $\gamma$-rays following ordinary (non-radiative) capture of negative muons by natural Se, Kr, Cd and Sm, as well as isotopically enriched $^{48}$Ti, $^{76}$Se, $^{82}$Kr, $^{106}$Cd and $^{150}$Sm targets was performed by means of HPGe detectors. Energy and time distributions were investigated and total life time of negative muon in different isotopes was deduced. Detailed analysis of $\gamma$-lines intensity allows to extract relative yield of several daughter nuclei and partial rates of ($\mu$,$\nu$) capture to numerous excited levels of the $^{48}$Sc, $^{76}$As, $^{82}$Br, $^{106}$Ag and $^{150}$Tc isotopes which are considered to be virtual states of an intermedia…
High-power production targets for the Super-FRS using a fast extraction scheme
2003
Abstract The high-power production target of the Super-FRS [H. Geissel et al., these Proceedings] will be irradiated by very intense heavy-ion beams which will be delivered from the future SIS100/200 [An International Accelerator Facility for Beams of Ions and Antiprotons, GSI-Report, 2001] synchrotron facility at the Gesellschaft fur Schwerionenforschung (GSI) Darmstadt. This paper presents calculations of the thermodynamic and the hydrodynamic response of such a target, considering that a uranium ion beam with an energy of 1 GeV/u and an intensity of 10 12 particles will impinge within 50 ns on a solid carbon target with a thickness of 4 g/cm 2 . Due to the high beam intensity the target …
A high power liquid hydrogen target for the Mainz A4 parity violation experiment
2005
We present a new powerful liquid hydrogen target developed for the precise study of parity violating electron scattering on hydrogen and deuterium. This target has been designed to have minimal target density fluctuations under the heat load of a 20$\mu$A CW 854.3 MeV electron beam without rastering the electron beam. The target cell has a wide aperture for scattered electrons and is axially symmetric around the beam axis. The construction is optimized to intensify heat exchange by a transverse turbulent mixing in the hydrogen stream, which is directed along the electron beam. The target is constructed as a closed loop circulating system cooled by a helium refrigerator. It is operated by a …
High brilliance uranium beams for the GSI FAIR
2017
The 40 years old GSI-UNILAC (Universal Linear Accelerator) as well as the heavy ion synchrotron SIS18 will serve as a high current heavy ion injector for the new FAIR (Facility for Antiproton and Ion Research) synchrotron SIS100. In the context of an advanced machine investigation program in combination with the ongoing UNILAC upgrade program, a new uranium beam intensity record (11.5 emA, ${\mathrm{U}}^{29+}$) at very high beam brilliance was achieved recently in a machine experiment campaign. This is an important step paving the way to fulfill the FAIR heavy ion high intensity beam requirements. Results of high current uranium beam measurements applying a newly developed pulsed hydrogen g…
Strength ofJπ=1+Gamow-Teller and isovector spin monopole transitions in double-β-decay triplets
2014
In this work we study systematically the energetics and intensity distributions of Gamow-Teller (GT${}^{\ifmmode\pm\else\textpm\fi{}}$) and isovector spin monopole (IVSM${}^{\ifmmode\pm\else\textpm\fi{}}$) transitions from the ground states of the pairs ($^{76}\mathrm{Ge}$,$^{76}\mathrm{Se}$), ($^{82}\mathrm{Se}$,$^{82}\mathrm{Kr}$), ($^{100}\mathrm{Mo}$,$^{100}\mathrm{Ru}$), ($^{116}\mathrm{Cd}$,$^{116}\mathrm{Sn}$), ($^{128}\mathrm{Te}$,$^{128}\mathrm{Xe}$), ($^{130}\mathrm{Te}$,$^{130}\mathrm{Xe}$), and ($^{136}\mathrm{Xe}$,$^{136}\mathrm{Ba}$), of double-beta-decay initial and final nuclei, to the ${J}^{\ensuremath{\pi}}={1}^{+}$ excited states of the intermediate odd-odd nuclei $^{76}\…
Fine structure in fragment mass-energy distribution from 238U+40Ar (275 MeV)
2003
Existence of a new feature in fragment mass-energy distribution is reported. Careful analysis of the data obtained in the reaction 238U + 40Ar (275 MeV) shows that small but statistically significant ripples visible already in the gross mass spectrum come from extended and regular 2D patterns in the TKE vs. mass matrix. Intensity distributions of these patterns coincide with the location of heavy clusters such as 78Ni, 108Mo, or 132Sn. Presumably, the observed patterns show the dominant trajectories in the elongation vs. mass-asymmetry space of the decaying system. This information, unknown in the past, can shed a new light even on the previously well-studied reactions.
Fractional-order theory of heat transport in rigid bodies
2014
Abstract The non-local model of heat transfer, used to describe the deviations of the temperature field from the well-known prediction of Fourier/Cattaneo models experienced in complex media, is framed in the context of fractional-order calculus. It has been assumed (Borino et al., 2011 [53] , Mongiovi and Zingales, 2013 [54] ) that thermal energy transport is due to two phenomena: ( i ) A short-range heat flux ruled by a local transport equation; ( ii ) A long-range thermal energy transfer proportional to a distance-decaying function, to the relative temperature and to the product of the interacting masses. The distance-decaying function is assumed in the functional class of the power-law …
Control of field-free molecular alignment by phase-shaped laser pulses
2005
We report an experimental study of the control of molecular alignment of ${\mathrm{N}}_{2}$ by use of spectrally modulated pulses at an intensity regime below the intrinsic saturation of the alignment. By manipulating the relative timing of the alignment revival pattern arising from the even subset of the thermal ensemble as compared to the odd subset, we demonstrate that the angular distribution of the aligned molecule can be converted into planar delocalization at specific times. We also show that the angular focusing of the molecular axis can be switched off by applying a specific bipulse.
Prediction of Swirling Flow in a Corrugated Channel
1991
Laminar and turbulent flow in a corrugated channel is simulated using HARWELL-FLOW3D. The channel represents a typical cell within a proposed design for the heat-transfer element of a rotary regenerator. Velocity vectors in planes perpendicular and parallel to the axis of a corrugation are visualised using Harwell’s graphics package, OUTPROC. Both programs were mn on Harwell’s Cray 2. The velocity vector plots show clear evidence of swirl, which is thought to be the mechanism responsible for the high rates of heat transfer in this type of heat-exchanger geometry. The swirl strength is shown to be a function of the channel geometry.
Laser control for the optimal evolution of pure quantum states
2005
Starting from an initial pure quantum state, we present a strategy for reaching a target state corresponding to the extremum (maximum or minimum) of a given observable. We show that a sequence of pulses of moderate intensity, applied at times when the average of the observable reaches its local or global extremum, constitutes a strategy transferable to different control issues. Among them, post-pulse molecular alignment and orientation are presented as examples. The robustness of such strategies with respect to experimentally relevant parameters is also examined.