A. R. Young

Ultracold neutron upscattering rates in a molecular deuterium crystal

A calculation of ultracold neutron (UCN) upscattering rates in molecular deuterium solids has been carried out, taking into account intramolecular excitations and phonons. The different molecular species ortho-

Performance of the prototype LANL solid deuterium ultra-cold neutron source

{D}_{2}

Three-dimensional imaging of spin polarization of alkali-metal vapor in optical pumping cells

(with even rotational quantum number J) and para-

Depolarization of ultracold neutrons during their storage in material bottles

{D}_{2}

Laser polarized muonic 3He and spin dependent μ− capture

(with odd J) exhibit significantly different UCN-phonon annihilation cross sections. Para- to ortho-

An apparatus to control and monitor the para-D2 concentration in a solid deuterium, superthermal source of ultra-cold neutrons

{D}_{2}

Positron production in heavy ion collisions: Current status of the problem

conversion, furthermore, couples UCN to an energy bath of excited rotational states without mediating phonons. This anomalous upscattering mechanism restricts the UCN lifetime to 4.6 msec in a normal-

Status of the new Los Alamos UCN source

{D}_{2}

A solenoidal spectrometer for positron-electron pairs produced in heavy-ion collisions

solid with 33% para content.

A combined polarized target/ionization chamber for measuring the spin dependence of nuclear muon capture in laser polarized muonic 3He

A prototype of a solid deuterium (SD 2 ) source of Ultra-Cold Neutrons (UCN) is currently being tested at LANSCE. The source is contained within an assembly consisting of a 4 K polyethylene moderator surrounded by a 77 K beryllium #ux trap in which is embedded a spallation target. Time-of-#ight measurements have been made of the cold neutron spectrum emerging directly from the #ux trap assembly. A comparison is presented of these measurements with results of Monte Carlo (LAHET/MCNP) calculations of the cold neutron #uxes produced in the prototype assembly by a beam of 800 MeV protons incident on the tungsten target. A UCN detector was coupled to the assembly through a guide system with a critical velocity of 8 m/s (58Ni). The rates and time-of-#ight data from this detector are compared with calculated values. Measurements of UCN production as a function of SD 2 volume (thickness) are compared with predicted values. The dependence of UCN production on SD 2 temperature and proton beam intensity are also presented. ( 2000 Elsevier Science B.V. All rights reserved.