Search results for "current"
showing 10 items of 2224 documents
A new representation of the Adler function for lattice QCD
2013
We address several aspects of lattice QCD calculations of the hadronic vacuum polarization and the associated Adler function. We implement a representation derived previously which allows one to access these phenomenologically important functions for a continuous set of virtualities, irrespective of the flavor structure of the current. Secondly we present a theoretical analysis of the finite-size effects on our particular representation of the Adler function, based on the operator product expansion at large momenta and on the spectral representation of the Euclidean correlator at small momenta. Finally, an analysis of the flavor structure of the electromagnetic current correlator is perform…
Inclusive electron scattering off 4He
2007
Inclusive electron scattering off 4He is investigated for low and medium energy and momentum transfers. The final state interaction, given by the simple semirealistic Malfliet-Tjon potential, is treated rigorously applying the Lorentz Integral Transform (LIT) method. Besides the nonrelativistic one-body current a consistent meson exchange current is constructed and implemented. Results are presented for both longitudinal and transverse response functions at various momentum transfers. Good agreement with experimental data is found for the longitudinal response function, while some strength is missing in the transverse response function on the low-energy side of the quasi-elastic peak.
Elektronenpolarisation im Energiebereich unterhalb 50 eV durch Streuung an freien Hg-Atomen
1966
The angular dependence of spin polarizationP(Θ) of electrons elastically scattered by a beam of mercury atoms is measured in a double scattering experiment for electron energies of 45±1 eV; 23±1 eV; 7±1 eV; and 3,5±1 eV. Maximum degree of polarization obtained isP(100°)=0,39±0,07; electron energy 7±1 eV; electron current 10−12–10−11 A.
Lower than low: Perspectives on zero- to ultralow-field nuclear magnetic resonance
2021
Abstract The less-traveled low road in nuclear magnetic resonance is discussed, honoring the contributions of Prof. Bernhard Blumich, aspiring towards reaching ‘a new low.’ A history of the subject and its current status are briefly reviewed, followed by an effort to prophesy possible directions for future developments.
Neutrino electron scattering and electroweak gauge structure: Future tests
1997
Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We propose the use of radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO, HELLAZ and LAMA. As an illustration, we display the sensitivity of these detectors in testing the possible existence of extra neutral gauge bosons, both in the framework of E_6 models and of models with left-right symmetry.
Speeding up liquid-phase heavy element chemistry: Development of a vacuum to liquid transfer chamber (VLTC)
2021
Abstract We present a new system, which is suitable for performing fast liquid phase chemistry experiments and gives access to shorter-lived isotopes of super heavy elements (SHE) than accessible with current techniques. With this novel vacuum to liquid transfer chamber (VLTC), which is mounted behind a physical preseparator, the desired isotopes are transported from the low-pressure side of the recoil separator directly into the liquid phase of a chemical experiment. Simulations on the kinematics of evaporation residues were performed using SRIM, validating the general plausibility of the VLTC concept. Subsequently, the feasibility was demonstrated with 250 , 252 Cf fission fragments, whic…
Optimal β-beam at the CERN-SPS
2005
A β-beam with maximum (for 6He ions) or (for 18Ne) could be achieved at the CERN-SPS. We study the sensitivity to and δ of such a beam as function of γ, optimizing with the baseline constrained to CERN–Frejus (130 km), and also with simultaneous variation of the baseline, for a fixed ion flux. These results are compared to the standard scenario previously considered, with lower , and also with a higher option that requires a more powerful accelerator. We conclude that the sensitivity to CP violation and increases significantly with γ if the baseline is increased proportionally, while for the CERN–Frejus scenario the dependence on γ is mild provided γ is above 100.
A $B_4C$-silicon target for the detection of neutrino interactions
1998
This note describes the construction of a target for neutrino interactions composed of passive boron carbide plates interleaved with silicon microstrip detectors. The target contains four layers of passive material with a total mass of 45 kg and 600 single--sided silicon microstrip detectors with a total surface of 1.14 m$^2$ distributed over five layers. It is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. During the 1997 run about 8000 \nm\ charged current interactions were estimated to have occurred in the target. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. This will provide invaluable experience towa…
Development and test of iron-free quadrupole lenses with high magnetic flux densities
2003
Abstract Iron-free magnetic quadrupole lenses have been developed for the focusing of energetic bunched heavy-ion beams. These devices are operated in a pulsed mode and provide very strong magnetic fields. A magnetic flux density of more than 14 T has been reached in a 100 mm long quadrupole with a 20 mm wide aperture, which corresponds to a magnetic flux density of ∼1400 T/m. The pulse duration of the applied electric current is approximately 300 μs with a flat top of several μs. The calculated and measured field properties of the quadrupoles are presented. In a first test experiment with a fast-extracted 650 MeV/u 197 Au 79+ beam (bunch length ∼500 ns) at GSI the focusing properties could…
Meson retardation in deuteron electrodisintegration
2004
The effect of meson retardation in $NN$-interaction and exchange currents on deuteron electrodisintegration is studied in a coupled channel approach including $NN$-, $N \Delta$- and $\pi d$-channels. It is shown that the influence of retardation depends on the energy regime: Whereas below $\pi$-threshold calculations with static and retarded operators yield almost identical results, they differ significantly in the $\Delta$-region. Especially, the longitudinal and the longitudinal-transverse interference structure functions are strongly affected.