Tailoring neutron beam properties by target-moderator-reflector optimisation

2021 ◽  
pp. 1-16
Author(s):  
Paul Zakalek ◽  
Jingjing Li ◽  
Sarah Böhm ◽  
Ulrich Rücker ◽  
Jörg Voigt ◽  
...  
Keyword(s):  
Neutron Beam ◽  
Heavy Water ◽  
Neutron Production ◽  
Neutron Sources ◽  
Light Water ◽  
Cold Neutrons ◽  
Efficient Coupling ◽  
Borated Polyethylene ◽  
Compact Design ◽  
Neutronic Performance

Compact accelerator-driven neutron sources allow to operate multiple optimised target-moderator-reflector (TMR) units adapted to the requirements of the respective instruments. The compact design of the TMR units allows an efficient coupling of neutron production, neutron moderation and extraction, but requires a novel way of optimisation. The neutronic performance of different TMR units based on polyethylene, heavy water and a mixture of heavy and light water moderators together with Pb and Be reflectors and a borated polyethylene absorber is discussed. Extraction channels for thermal and cold neutrons are investigated regarding the energy and time spectra.

scholarly journals Three- and Four-Site Models for Heavy Water: SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW

2021 ◽  
Author(s):  
Johanna-Barbara Linse ◽  
Jochen S. Hub
Keyword(s):  
Molecular Dynamics ◽  
Heavy Water ◽  
Room Temperature ◽  
Deuterium Oxide ◽  
Water Structure ◽  
Light Water ◽  
Pair Potentials ◽  
Effective Pair ◽  
Water Models ◽  
Dynamics Simulations

Heavy water or deuterium oxide, D<sub>2</sub>O, is used as solvent in various biophysical and chemical experiments. To model such experiments with molecular dynamics simulations, effective pair potentials for heavy water are required that reproduce the well-known physicochemical differences relative to light water. We present three effective pair potentials for heavy water, denoted SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW. The models were parametrized by modifying widely used three- and four-site models for light water, with aim of maintaining the specific characteristics of the light water models. At room temperature, the SPC/E-HW and TIP3P-HW capture the modulations relative to light water of the mass and electron densities, heat of vaporization, diffusion coefficient, and water structure. TIP4P/2005-HW captures in addition the density of heavy water over a wide temperature range.

scholarly journals Three- and Four-Site Models for Heavy Water: SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW

2021 ◽  
Author(s):  
Johanna-Barbara Linse ◽  
Jochen S. Hub
Keyword(s):  
Molecular Dynamics ◽  
Heavy Water ◽  
Room Temperature ◽  
Deuterium Oxide ◽  
Water Structure ◽  
Light Water ◽  
Pair Potentials ◽  
Effective Pair ◽  
Water Models ◽  
Dynamics Simulations

Heavy water or deuterium oxide, D<sub>2</sub>O, is used as solvent in various biophysical and chemical experiments. To model such experiments with molecular dynamics simulations, effective pair potentials for heavy water are required that reproduce the well-known physicochemical differences relative to light water. We present three effective pair potentials for heavy water, denoted SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW. The models were parametrized by modifying widely used three- and four-site models for light water, with aim of maintaining the specific characteristics of the light water models. At room temperature, the SPC/E-HW and TIP3P-HW capture the modulations relative to light water of the mass and electron densities, heat of vaporization, diffusion coefficient, and water structure. TIP4P/2005-HW captures in addition the density of heavy water over a wide temperature range.

Tritium Decontamination of Contaminated System With Tritiated Heavy Water by Drying Treatment

2016 ◽  
Author(s):  
Haruhiko Kadowaki ◽  
Akira Matsushima ◽  
Yoshiaki Nakajima
Keyword(s):  
Heavy Water ◽  
Water Purification ◽  
Thermal Reactor ◽  
Vacuum Drying ◽  
Light Water ◽  
Long Period ◽  
Water Purification System ◽  
Purification System ◽  
Drying Treatment ◽  
Rotary Type

Advanced thermal reactor “FUGEN” is a heavy water-moderated boiling light water-cooled pressure tube-type reactor. Because tritium had been generated in the heavy water during the reactor operation, the heavy water system and helium system were contaminated by tritium. The chemical form of the tritium was water molecule in FUGEN. For the drying treatment of heavy water contaminated by tritium, air-through drying and vacuum drying were applied to the system drying. The air-through drying has an advantage that can reduce the risk of tritium leakage, because the drying equipment can be constructed as closed-circuit. On the other hand, the vacuum drying can dry the whole system because dead end of piping can be aspirated. Helium system, heavy water purification system and rotary type dehumidifier were chosen for the object in this study. It was demonstrated that both methods were effective for drying treatment of heavy water in system. Helium system, low-contamination and non inclusion, could finish the vacuum drying rapidly. However, Heavy water purification system needed long period for drying treatment. The result showed that it needed long period to dry up if the objects include the adsorbent of water such as alumina pellet, resin and silica gel. But it can be accelerated by replacement absorbed heavy water to light water from the result of drying treatment of the rotary type dehumidifier.

POSSIBILITY OF A SMALL NEUTRON SOURCE BY LASER-PLASMA INTERACTION

2007 ◽  
Vol 21 (03n04) ◽  
pp. 600-608
Author(s):  
Y. IWASHITA ◽  
S. NAKAMURA ◽  
K. YAMADA ◽  
A. OGATA ◽  
Y. WADA ◽  
...  
Keyword(s):  
Laser Plasma ◽  
Threshold Energy ◽  
Neutron Sources ◽  
Laser Plasma Interaction ◽  
Cold Neutrons ◽  
New Ideas ◽  
Deuterated Polyethylene ◽  
Under Construction ◽  
Low Irradiation ◽  
Good Probe

Cold neutrons are good probe for nano meter scale objects. While some huge facilities as spallation neutron sources are under construction, small local (satellite) neutron sources will help to test new ideas on research. Such small ones are considered to be complementary parts of the huge facilities. Because the threshold energy of the d-d reactions is fairly low, irradiation of deuterated polyethylene (CD2) target by laser induced energetic deuterons may generate neutrons. A preliminary experiment performed with 1TW laser irradiating CD2 foil just before another thick CD2 target is described.

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