Energy per ion pair measurements in pure helium and helium mixtures

Journal Article · Thu Apr 01 00:00:00 EST 1976 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3574351· OSTI ID:7359893

Harris, S J; Doust, C E

Discrepancies exist between the many published measurements of anti W, the average energy to produce an ion pair for helium. Since results for other gases have been relatively consistent, the cause of the discrepancies usually has been attributed to the need to use ultrapure helium in order to avoid Penning ionization. This arises from the deexcitation of highly excited metastable states by collisions with contaminant atoms. A new experimental value of anti W has been established as 43.5 +- 0.3 eV per ion pair for /sup 241/Am alpha particles completely stopped in purified helium. Particular attention has been paid to the establishment and maintenance of pure helium. The present result agrees well with theoretical predictions corrected for molecular ion formation. Gas mixture studies have been made which indicate that nonmetastable excited states of helium are responsible in part for the Penning ionization effect, previously attributed to metastable states alone.

• Research Organization: Univ. of Surrey, Guildford, Eng.
• OSTI ID: 7359893
• Journal Information: Radiat. Res.; (United States), Vol. 66:1
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA PARTICLES
ENERGY LOSSES
HELIUM
CHARGED-PARTICLE TRANSPORT
ION PAIRS
METASTABLE STATES
PENNING EFFECT
CHARGED PARTICLES
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
NONMETALS
RADIATION TRANSPORT
RARE GASES
654001* - Radiation & Shielding Physics- Radiation Physics
Shielding Calculations & Experiments