562 research outputs found
The PolFusion Experiment: Measurement of the d-d-Fusion Spin-Dependence
No full textA double-polarized dd-fusion experiment is under preparation at PNPI,
Gatchina. The experimental program includes themeasurements of the asymmetry in
the differential cross section of the reactions d_pol + d_pol → 3He + n and d_pol + d_pol → t + p. The spin-correlation coefficients Cz,z and Czz,zz will be measured to determine
the quintet-state suppression factors for both reactions, for which quite different
theoretical predictions were made and which are very important for the design of
future neutron-lean fusion reactors. The total cross sectionmodification for polarized
d–d fusion will also be investigated. An increase by a factor of 1.5 was already
deduced for the d + 3He and the d + t reactions. The experimental setup and the
future upgrade plans are described
Optimization and first tests of the experimental setup to investigate the double-polarized DD-fusion reactions
No full textThe study of DD reactions, especially with polarized reactants, helps for better understanding of the processes taking place in nuclear astrophysics and fusion reactors. At PNPI Gatchina, Russia, the PolFusion experiment with crossing of two polarized beams, i.e. a deuteron and a deuterium beam, is able to measure angular distributions of the differential cross section and, therefore, the spin-correlations coefficients with different combinations of the adjustable nuclear polarization of both beams with a center-of-mass energy between 10 to 100 keV. Some improvements and fine-tuning of the polarized ion source are performed and presented. The atomic beam source for the jet target has been modified as well. An unpolarized experiment with a 10 keV ion beam and heavy water vapor as a target has been carried out with successful registration of the fusion products
Production of HD Molecules in Definite Hyperfine Substates
No full textPolarized atomic beam sources have been in operation for many years to produce either nuclear polarized atomic hydrogen or deuterium beams. In recent experiments, such a source was used to polarize both isotopes independently at the same time. By recombination of the atoms, hydrogen-deuterium molecules with all possible nuclear spin combinations can be created. Those spin isomers are useful for further applications, like precision spectroscopy, as polarized targets for laser-particle acceleration, polarized fuel for fusion reactors, or as an option for future measurements of electric dipole moments
Production and storage of polarized H, D, and HD molecules
No full textThe investigation of the recombination of nuclear polarized hydrogen and deuterium atoms into polarized molecules gives new insights into different fields in physics and chemistry. On the one hand, the measurement of the polarization preservation during the recombination process itself allows one the observation of a new parameter during the chemical processes on different surfaces and enables the production of hyper-polarized molecules. On the other hand, the molecular polarization measured as a function of the imposed external magnetic field delivers the coupling forces of the nuclear spins and the rotational magnetic moments of the molecules as well as the coupling between the two nuclear spins themselves. This knowledge allows one to optimize storage-cell gas targets for coming accelerators experiments or to produce and handle polarized fuel for future fusion reactors
Hyper-Polarized Deuterium Molecules: An Option to Produce and Store Polarized Fuel for Nuclear Fusion?
No full textPolarized fusion
No full textSince more than 50 years it has been discussed to increase the gain of nuclear fusion reactors with the use of polarized fuel. For example, the total cross sections of the fusion reactions d + t → 4He + n or 3He + d → 4He + p are increased by a factor of about 1.5 if the spins of both incoming particles are aligned. But before polarized fuel can be used for energy production in the different types of reactors, a number of questions must be answered. In this contribution we give an overview on our various activities in this field of researc
Jet-like correlations with direct-photon and neutral-pion triggers at sNN=200 GeV
No full textAbstractAzimuthal correlations of charged hadrons with direct-photon (γdir) and neutral-pion (π0) trigger particles are analyzed in central Au+Au and minimum-bias p+p collisions at sNN=200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p+p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γdir trigger is independent of the transverse momentum of the trigger particle (pTtrig), whereas the suppression is smaller at low transverse momentum of the associated charged hadrons (pTassoc). Within uncertainty, similar levels of suppression are observed for γdir and π0 triggers as a function of zT (≡pTassoc/pTtrig). The results are compared with energy-loss-inspired theoretical model predictions. Our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy
Optimization and first tests of the experimental setup to investigate the double-polarized DD-fusion reactions
No full textThe study of DD reactions, especially with polarized reactants, helps for better understanding of the processes taking place in nuclear astrophysics and fusion reactors. At PNPI Gatchina, Russia, the PolFusion experiment with crossing of two polarized beams, i.e. a deuteron and a deuterium beam, is able to measure angular distributions of the differential cross section and, therefore, the spin-correlations coefficients with different combinations of the adjustable nuclear polarization of both beams with a center-of-mass energy between 10 to 100 keV. Some improvements and fine-tuning of the polarized ion source are performed and presented. The atomic beam source for the jet target has been modified as well. An unpolarized experiment with a 10 keV ion beam and heavy water vapor as a target has been carried out with successful registration of the fusion products
CRYOGENIC SYSTEM FOR PRECISE CALIBRATION OF TEMPERATURE SENSORS
No full textA calibration technique for cryogenic temperature sensors is proposed and implemented. The experimental setup is based on the helium cryogenerator, providing calibration of the temperature sensors of various types in wide temperature range, including cryogenic band (25-100K). A condensation thermometer with hydrogen, neon, argon and xenon as working gases is used as a reference sensor. The experimental setup was successfully used for precise (0.1K precision) calibration of platinum resistive temperature detectors (Pt-100) for international nuclear physics experiments MuSun and PolFusion. The setup can also be used for calibration of temperature sensors of the other types
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