Inclusive measurement of (p,. pi. /sup -/xn) double charge exchange reactions on bismuth from threshold to 800 MeV
The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,..pi../sup -/xn) double charge exchange reactions on bismuth (/sup 209/Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of /sup 211/At activity in thin (approx.1 mg/cm/sup 2/), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed /sup 211/At activity although even at the highest energies, the contribution to products lighter than /sup 207/At was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product (/sup 210/At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about /sup 204/At. The most probable momentum transfer deduced from these distributions for the initial ..pi../sup -/ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of /sup 210/Po from a (p,..pi../sup 0/) reaction on /sup 209/Bi, but radically different from that observed for inclusive ..pi../sup -/ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.
- Research Organization:
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
- OSTI ID:
- 5666951
- Journal Information:
- Phys. Rev. C; (United States), Vol. 32:1
- Country of Publication:
- United States
- Language:
- English
Similar Records
Inclusive. pi. /sup -/ production with 200 MeV protons: Radiochemical study of the /sup 209/Bi(p,. pi. /sup -/xn)/sup 210-x/ At reactions
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Related Subjects
BISMUTH 209 TARGET
PROTON REACTIONS
CHARGE-EXCHANGE REACTIONS
ASTATINE 210
ASTATINE 211
ENERGY DEPENDENCE
MEV RANGE 100-1000
NEUTRONS
PARTICLE PRODUCTION
PIONS MINUS
PIONS NEUTRAL
RADIOASSAY
RADIOCHEMICAL ANALYSIS
TOTAL CROSS SECTIONS
ALPHA DECAY RADIOISOTOPES
ASTATINE ISOTOPES
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BOSONS
CHARGED-PARTICLE REACTIONS
CHEMICAL ANALYSIS
CROSS SECTIONS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRON REACTIONS
HADRONS
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
ISOTOPES
MESONS
MEV RANGE
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PIONS
PSEUDOSCALAR MESONS
QUANTITATIVE CHEMICAL ANALYSIS
RADIOISOTOPES
TARGETS
651925* - Nuclear Properties & Reactions
A=190-219
Experimental- Nuclear Reactions & Scattering- (-1987)