Sensitivity studies of the ortho/para H{sub 2} concentration on the neutronic performance of the Lujan center liquid H{sub 2} moderator using state-of-the-art computational tools

Conference · Thu Jan 01 04:00:00 EST 1998

OSTI ID:674722

Russell, G. J.; Ferguson, P. D.; Pitcher, E. J.

A liquid H{sub 2} moderator has been operational at the Manual Lujan Jr. Neutron Scattering Center (Lujan Center) since 1985. Detailed Monte Carlo calculations have been made to estimate the neutronic performance of the liquid H{sub 2} moderator cold source, using the state-of-the-art Los Alamos LAHET Code System and liquid H{sub 2} scattering kernels. The absolute neutron spectrum leaking from the moderator has been measured. In thermal equilibrium at 20 K, the moderator would convert to 100% para-hydrogen on some time frame. The authors show that the performance of the Lujan Center cold neutron source is sensitive to small fractions of ortho-hydrogen, and display these results as a function of the ortho/para H{sub 2} concentration. Integral data from the measured neuron spectrum have been combined with calculated predictions to estimate the ortho/para H{sub 2} concentration in the moderator. From these analyses, they estimate the ortho-hydrogen concentration in the liquid H{sub 2} moderator to be 6--9% at the time the neutron spectrum was measured.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Management and Administration, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 674722
• Report Number(s): LA-UR--98-1021; CONF-9709132--; IWCMPNS--1997; ON: DE98006322
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
43 PARTICLE ACCELERATORS
ACCELERATOR FACILITIES
COLD NEUTRONS
HYDROGEN
MODERATORS
NEUTRON LEAKAGE
NEUTRON SOURCES
NEUTRON SPECTRA
SENSITIVITY ANALYSIS
SPIN