Monoenergetic positronium beams and laboratory simulations of galactic positron annihilation
A monoenergetic positronium (Ps) beam, useful for Ps-surface diffraction studies and scattering experiments, is introduced and demonstrated. Also, a series of experiments simulating a neutral galactic positron-annihilation medium is presented. Calculations show that the novel monoenergetic Ps beam created in a gas has an energy width limited only by current positron-beam technology. Monoenergetic triplet positronium, created in He, is detected with an annihilation plate (or a channel plate) and two scintillation detectors. The observation of the singlet annihilation spectrum indicates that the beam is narrow in energy and that the angular distribution agrees with theory. The simulation of a galactic annihilation medium for positrons is effected by study of positrons slowing down in low-density gases. The annihilation linewidth was measured for Ps, formed by positrons slowing down from high energies in H/sub 2/ and He. The fraction of positrons that survives below the threshold for Ps formation was measured with a pulsed-beam technique. The linewidth for positrons directly annihilating with bound electrons in H/sub 2/ was measured with another pulsing technique.
- Research Organization:
- Brandeis Univ., Waltham, MA (USA)
- OSTI ID:
- 7128529
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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