Finite size corrections to the equation of state for nuclear matter near the phase transition hadron gas to quark gluon plasma

It is widely accepted that the finite size of the hadrons must be taken into account in a thermodynamic description of the hadron gas near the phase transition to quark gluon plasma. Existing thermodynamic models introducing a .correction due to the finite size of the particles are reviewed and discussed. A new model to describe dense nuclear matter is developed. The model takes into account the different quantum statistical distributions of the hadrons. The grand canonical pressure partition function is used. to obtain the thermodynamic limit. The grand canonical partition function is restricted so that only those states where the extended particles fit into the volume of the system, are counted. The configuration space is reduced accordingly. The hadrons are described as MIT bags. The size of the particles depends on the pressure in the system. The pressure in the system compresses the hadrons which leads to an increase of the mass of the hadrons according to the MIT bag equation. The size of the particles is determined by the minimum of the grand canonical potential. A consistent thermodynamic theory is obtained. The equation of state for hadronic matter is discussed for the special cases, zero temperature and zero chemical potential, before the general case of finite temperature and finite chemical potential is used to construct a first order phase transition from hadron gas to quark gluon plasma. At high densities the influence of the description of the hadrons as MIT bags becomes significant. It is found that the phase transition is strongly dependent on the value chosen for the bag constant and the application of as corrections. Therefore ~reliable value of the bag constant and a generally accepted theory for as corrections are essential to obtain a good thermodynamic description of the phase transition from hadron gas to quark gluon plasma

Study of ³He Rabi nutations by optically-pumped cesium magnetometers

We describe a method for recording the Rabi nutation of nuclear spin polarized ³He by optically pumped cesium magnetometers. The measurement is performed by detecting the time-dependent magnetic field produced by the 3He magnetization. The observed signals are compared to theoretical models and the results are used to precisely trace the evolution of the magnetization. This procedure represents a convenient way to control and measure the Rabi flip angle and the degree of spin polarization in experiments using 3He magnetometers. The method requires only very coarse knowledge of the applied magnetic field’s magnitude

Design and performance of an absolute 3He/Cs magnetometer

We report on the design and performance of a highly sensitive combined ³He/Cs magnetometer for the absolute measurement of magnetic fields. The magnetometer relies on the magnetometric detection of the free spin precession of nuclear spin polarized ³He gas by optically pumped cesium magnetometers. We plan to deploy this type of combined magnetometer in an experiment searching for a permanent electric dipole moment of ultracold neutrons at the Paul-Scherrer Institute (Switzerland). A prototype magnetometer was built at the University of Fribourg (Switzerland) and tested at Physikalisch-Technische Bundesanstalt (Berlin, Germany). We demonstrate that the combined magnetometer allows Cramér-Rao-limited field determinations with recording times in the range of, measurements above being limited by the stability of the applied magnetic field. With a recording time we were able to perform an absolute measurement of a magnetic field of ≈ with a standard uncertainty of, corresponding to ΔB/B < 6 ×10⁻⁸

Investigation of the intrinsic sensitivity of a ³He/Cs magnetometer

We report on extensive studies on the intrinsic sensitivity of a combined ³He/Cs magnetometer. The magnetometer relies on the detection of the free spin precession of nuclear spin polarized ³He by optically pumped cesium magnetometers. We characterize the relevant processes involved in the detection and quantify their impact on the total sensitivity of the magnetometer. An expression is derived that predicts the sensitivity of this magnetometer scheme and the results are compared to experiments. Excellent agreement is found between theory and experiments, and implications for an application of a ³He/Cs magnetometer in an experiment searching for a permanent neutron electric dipole moment are discussed

PicoTesla absolute field readings with a hybrid 3He/87Rb magnetometer

We demonstrate the use of a hybrid 3He/87 magnetometer to measure absolute magnetic fields in the pT range. The measurements were undertaken by probing time-dependent 3He magnetisation using 87Rb zero-field magnetometers. Measurements were taken to demonstrate the use of the magnetometer in cancelling residual fields within a magnetic shield. It was shown that the absolute field could be reduced to the 10 pT level by using field readings from the magnetometer. Furthermore, the hybrid magnetometer was shown to be applicable for the reduction of gradient fields by optimising the effective 3He T2 time. This procedure represents a convenient and consistent way to provide a near zero magnetic field environment which can be potentially used as a base for generating desired magnetic field configurations for use in precision measurements

Infrared Mn I laboratory oscillator strengths for the study of late type stars and ultracool dwarfs

Original article can be found at: http://www.aanda.org/ Copyright The European Southern ObservatoryAims: The aim of our new laboratory measurements is to measure accurate absolute oscillator strengths for neutral manganese transitions in the infrared needed for the study of late-type stars and ultracool dwarfs. Methods: Branching fractions have been measured by high resolution Fourier transform spectroscopy and combined with radiative level lifetimes in the literature to yield oscillator strengths. Results: We present experimental oscillator strengths for 20 transitions in the wavelength range 3216 to 13 997 Å, 15 of which are in the infrared. The transitions at 12 899 Å  and 12 975 Å  are observed as strong features in the spectra of late-type stars and ultracool dwarfs. We have fitted our calculated spectra to the observed lines in spectra of late-type stars. Using the new experimentally measured log(gf) values together with existing data for hyperfine structure splitting factors we determined the manganese abundance to be log N(Mn) = -6.65 ± 0.05 in the atmosphere of the Sun, log N(Mn) = 6.95 ± 0.20 in the atmosphere of Arcturus, and log N(Mn) = -6.70 ± 0.20 in the atmosphere of M 9.5 dwarf 2MASSW 0140026+270150.Peer reviewe