High-resolution, vacuum-ultraviolet absorption spectrum of boron trifluoride.

In the course of investigations of thermal neutron detection based on mixtures of (10)BF3 with other gases, knowledge was required of the photoabsorption cross sections of (10)BF3 for wavelengths between 135 and 205 nm. Large discrepancies in the values reported in existing literature led to the absolute measurements reported in this communication. The measurements were made at the SURF III Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology.

The Detection of Lyman Alpha Radiation Formed by the Slowing Down of Protons and Tritons Produced by the (3)He (n, tp) Reaction-A Model Study.

The observation of Lyman alpha (Lα) radiation produced by the end products of the (3)He (n,tp) reaction has suggested the possibility of a new method of cold thermal neutron detection. In order for this goal to be achieved, a basic understanding of how the Lα radiation is formed and how it may be detected, is needed. The model study described here is an attempt to provide this basic understanding and to provide quantitative results that can be used in designing future experiments.

Observation of the (3)He(n, tp) Reaction by Detection of Far-Ultraviolet Radiation.

We have detected Lyman alpha radiation, 121.6 nm light produced from the n = 2 to n = 1 transition in atomic hydrogen, as a product of the (3)He(n, tp) nuclear reaction occurring in a cell of (3)He gas. The predominant source of this radiation appears to be decay of the 2p state of tritium produced by charge transfer and excitation collisions with the background (3)He gas.