A laboratory-based pulsed positron beam that will be employed in an n=2 positronium spectroscopy experiment has been fully developed and tested. Moderated positrons from a radioactive source are accumulated in a cylindrical Penning trap with a slowly-ramped electric potential applied to the source assembly. The accumulation efficiency is found to be 10-45% for repetition rates of 100 - 670 Hz yielding positron pulse widths of {approximately} 25 ns (FWHM). The accumulation process, however, increases the transverse velocity of the beam which consequently raises the background-positron noise in the spectroscopy experiment. Furthermore, the precision of this measurement greatly suffers if conducted in a large magnetic field. Therefore, the pulsed beam is extracted to a magnetic-field-free region, focused, and remoderated using a Ni crystal. This remoderated pulsed beam is subsequently focused on to a < 2 mm diameter (FWHM) spot with a combined remoderation and transport efficiency of {approximately} 13%.

Results from a positron accumulator that operates efficiently over a range of repetition rates from 100 to 1000 Hz are presented. Moderated β‐decay positrons from a radioactive source are accumulated in a Penning‐style trap. At a repetition rate of 250 Hz an accumulation efficiency of ∼25% has been achieved. Two techniques for reducing the time spread of the positron pulses have been investigated. The most successful method reduces the pulse width from 120 ns to 20 ns.

A pulsed source of positrons has been developed which may be useful for antihydrogen (\(\bar H\)) formation because it is portable when compared to accelerator-based sources. This positron accumulator uses a Penning-style trap to collect moderated positrons from a radioactive source. The positron pulses may be emitted with repetition rates in the range of 50–1000 Hz, which is appropriate for\(\bar H\) production schemes involving laser-induced recombination. Bunching techniques may be used to vary the width of the positron pulses over the range 30–120 ns (FWHM) to match the width of the antiproton and/or laser pulses. The efficiency of the accumulator increases from ∼ 10% at 100 Hz to ∼ 50% at 1000 Hz. 250 Hz the efficiency is ∼ 25% and the accumulator has delivered up to 8 e+/pulse per mCi of positron activity. This translates into ∼ 1.2 × 105 e+/pulse for a 100 Ci58Co source.

The formation of n = 2 positronium is investigated using a positron beam incident on a variety of untreated metal foils and crystals. The maximum measured formation fraction is much higher than any previously reported for such targets. Fully 2% of the incident positrons are observed to form n = 2 positronium at low input energy with little dependence upon the metal substrate of the formation surface. The n = 2 positronium spectra exhibit lifetime components characteristic of two distinct populations with different kinetic energies. The dependence of each of these components on the incident positron energy is studied and interpreted as being consistent with existing theories of positron interactions with metals. The production of n = 2 positronium using positrons transmitted through metal meshes and thin foils is also observed and discussed briefly.

There are many important applications for very intense positron beams (≥ I Ci of e+); however, the radioactive sources needed to produce these beams are not readily available. Two separate processes for fabricating inexpensive, intense positron sources from 22Na and 58Co have been investigated. Both procedures have been successfully tested with low levels (mCi) of activity.

A design for a two-stage positron accumulator is presented. The first stage employs remoderation cooling of positrons while the second stage utilizes electron cooling. The device is designed to produce intense pulses of positrons at low repetition rates (1–100 Hz). Preliminary results from tests on the first stage are presented.

A method of removing22Na from Al via distillation is investigated. Distillation is rapid (≈10 minutes) and nearly quantitative. When the distilled vapor is directed by a flow of He gas the deposit may be localized fairly well and easily recovered with water.

The formation of antihydrogen (\(\overline H\)) is of interest for a variety of reasons. Properties of the \(\overline H\) such as the electronic energy levels, fine structure, Lamb shift, and hyperfine structure can be measured and compared to the corresponding quantities in hydrogen as tests of CPT invariance. Novel investigations of the interactions of \(\overline H\) with atoms and with gravitation can be undertaken. Finally, applications such as the production of polarized antiprotons or the storage of macroscopic quantities of \(\overline H\) can also be pursued.