T-T Neutron Spectrum from Inertial Confinement Implosions

Measurements of the T(2n,)$^4$He reaction (TT) have been conducted using high-purity tritium, gas-filled capsules in inertial confinement fusion (ICF) implosions. At the OMEGA laser facility, TT neutron spectra were measured using two instruments: the neutron-time-of-flight (nTOF) facility and the Magnetic Recoil Spectrometer (MRS) facility. The resolutions of these systems were improved for nTOF by using a crystal with much faster decay time and for MRS by using a thinner, more uniform CD2 recoil foil. Measurements at c.m. energies of 10-30 keV can be used to study the TT three-body reaction mechanism near astrophysical energies. With both nTOF and MRS, we observe a small, narrow peak starting at the 9.44 MeV endpoint, corresponding to the n + $^5$He (g.s.) reaction channel. Most of the TT reaction proceeds through other reaction channels which produce broad, continuous neutron spectra in the range 0 - 9.5 MeV. Implications for ICF experiments at the National Ignition Facility will be discussed. Work in collaboration with J. A. Frenje, D. T. Casey, M. J.-E. Manuel, N. Sinenian, A. B. Zylstra, F. H. Seguin, C. K. Li, R. D. Petrasso, V. Yu Glebov, P. B. Radha, D. D. Meyerhofer, T. C. Sangster, P. A. Amendt, R. Hatarik, D. B. Sayre, J. R. Rygg, H. W. Herrmann and Y. H. Kim.