The lifetime of the neutron and primordial nucleosynthesis

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Bulletin of the American Physical Society

OSTI ID:243707

Smith, M S ^[1]

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1. Oak Ridge National Lab., TN (United States)

A Monte Carlo analysis has been used to investigate the possible effect of a new neutron lifetime ({tau}{sub n}) measurement (in progress) on predictions of the Standard Big Bang Nucleosynthesis (SBBN) Model. It is found that the statistical 1-{sigma} uncertainty {sigma}{sub {tau}} = 1.9 s in the current weighted mean value {tau}{sub n} = 888.5 s contributes only 40% of the predicted 2-{sigma} uncertainty in Y{sub p}, not {ge} 90% as previously claimed. A new measurement decreasing {sigma}{sub {tau} to 1 s would decrease the Y{sub p} uncertainty by 27% but would have a negligible effect (3% decrease) on the upper bound on the cosmological baryon density parameter {Omega}{sub b}. For {sigma}{sub {tau}} = 1 s, 80% of the Y{sub p} uncertainty is due to nuclear reaction rate uncertainties - primarily p(n, {gamma})d, d(d,p)t, and d(d,n){sup 3}He. This lessens the importance of decreasing {sigma}{sub {tau}} from the perspective of SBBN. Furthermore, a large range of neutron lifetimes are found to be consistent with the primordial D + {sup 3}He and {sup 4}He abundance limits inferred from observations: for {sigma}{sub tau}} = 1 s, values of {tau}{sub n} {le} 898.5 s are allowed.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 243707
• Report Number(s): CONF-9304297--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 2 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COSMOLOGICAL MODELS
LIFETIME
NEUTRONS
NUCLEOSYNTHESIS