Electron energy distribution in photolytically pumped lasers

Morgan, W. L.; Franklin, Ross; Haas, Randall

doi:10.1063/1.92122

“…The above argument sets lower limits on the masses of new Z ′ gauge bosons to which right-handed neutrinos would be coupled in models of superstrings [98], or extended technicolor [99]. Similarly a Dirac magnetic moment for neutrinos, which would allow the right-handed states to be produced through scattering and thus increase g * , can be significantly constrained [100], as can any new interactions for neutrinos that have a similar effect [101]. Right-handed states can be populated directly by helicity-flip scattering if the neutrino mass is large enough, and this property has been used to infer 1.…”

Section: Beyond the Standard Modelmentioning

confidence: 99%

Big-Bang Nucleosynthesis

Fields,

Molaro,

Sarkar

2014

Preprint

View full text Add to dashboard Cite

Big-Bang nucleosynthesis (BBN) offers the deepest reliable probe of the early Universe, being based on well-understood Standard Model physics [1]. Predictions of the abundances of the light elements, D, 3 He, 4 He, and 7 Li, synthesized at the end of the 'first three minutes', are in good overall agreement with the primordial abundances inferred from observational data, thus validating the standard hot Big-Bang cosmology (see [2][3][4] for reviews). This is particularly impressive given that these abundances span nine orders of magnitude -from 4 He/H ∼ 0.08 down to 7 Li/H ∼ 10 −10 (ratios by number). Thus BBN provides powerful constraints on possible deviations from the standard cosmology, and on new physics beyond the Standard Model [5][6][7][8].

show abstract

“…The reported results do not end the possible role of superelastic collisions in affecting the eedf. Other important applications concern the role of skc in determining negative electron mobility [56] as well as the properties of the plasma formed in the interaction of a resonant laser with alkaline atoms [57,58].…”

Section: Discussionmentioning

confidence: 99%

Electron energy distribution functions and second kind collisions

Capitelli¹,

Colonna²,

Pascale³

et al. 2008

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

The role of second kind collisions (skc) in affecting the electron energy distribution function (eedf) is discussed in the light of old and new results. Different non-equilibrium situations are presented including low pressure and atmospheric plasmas. Special attention is devoted to the post-discharge conditions when the decay of electron temperature is such as to emphasize the role of skc in structuring the eedf. Finally, results for parallel plate reactors obtained by including self-consistent kinetics in a particle in cell with Monte Carlo collisions approach and 1D high enthalpy flows for aerospace applications are presented and discussed.

show abstract

“…The above argument sets lower limits on the masses of new Z ′ gauge bosons to which right-handed neutrinos would be coupled in models of superstrings [98], or extended technicolor [99]. Similarly a Dirac magnetic moment for neutrinos, which would allow the right-handed states to be produced through scattering and thus increase g * , can be significantly constrained [100], as can any new interactions for neutrinos that have a similar effect [101]. Right-handed states can be populated directly by helicity-flip scattering if the neutrino mass is large enough, and this property has been used to infer a bound of m ν τ < ∼ 1 MeV taking N ν < 4 [102].…”

Section: +034mentioning

confidence: 99%

Big Bang Nucleosynthesis

Jedamzik

¹

SpringerReference

0

View full text Add to dashboard Cite

Big-Bang nucleosynthesis (BBN) offers the deepest reliable probe of the early Universe, being based on well-understood Standard Model physics [1]. Predictions of the abundances of the light elements, D, 3 He, 4 He, and 7 Li, synthesized at the end of the 'first three minutes', are in good overall agreement with the primordial abundances inferred from observational data, thus validating the standard hot Big-Bang cosmology (see [2][3][4] for reviews). This is particularly impressive given that these abundances span nine orders of magnitude -from 4 He/H ∼ 0.08 down to 7 Li/H ∼ 10 −10 (ratios by number). Thus BBN provides powerful constraints on possible deviations from the standard cosmology, and on new physics beyond the Standard Model [5-8]. TheoryThe synthesis of the light elements is sensitive to physical conditions in the early radiation-dominated era at a temperature T ∼ 1 MeV, corresponding to an age t ∼ 1 s. At higher temperatures, weak interactions were in thermal equilibrium, thus fixing the ratio of the neutron and proton number densities to be n/p = e −Q/T , where Q = 1.293 MeV is the neutron-proton mass difference. As the temperature dropped, the neutron-proton inter-conversion rate per nucleon, Γ n↔p ∼ G 2 F T 5 , fell faster than the Hubble expansion rate, H ∼ √ g * G N T 2 , where g * counts the number of relativistic particle species determining the energy density in radiation (see 'Big Bang Cosmology' review). This resulted in departure from chemical equilibrium ('freeze-out') at T fr ∼ (g * G N /G 4 F ) 1/6 ≃ 1 MeV. The neutron fraction at this time, n/p = e −Q/T fr ≃ 1/6, is thus sensitive to every known physical interaction, since Q is determined by both strong and electromagnetic interactions while T fr depends on the weak as well as gravitational interactions. Moreover, the sensitivity to the Hubble expansion rate affords a probe of, e.g., the number of relativistic neutrino species [9]. After freeze-out, the neutrons were free to β-decay, so the neutron fraction dropped to n/p ≃ 1/7 by the time nuclear reactions began. A simplified analytic model of freeze-out yields the n/p ratio to an accuracy of ∼ 1% [10,11].The rates of these reactions depend on the density of baryons (strictly speaking, nucleons), which is usually expressed normalized to the relic blackbody photon density as η ≡ n b /n γ . As we shall see, all the light-element abundances can be explained with η 10 ≡ η × 10 10 in the range 5.7-6.7 (95% CL). With n γ fixed by the present CMB temperature 2.7255 K (see 'Cosmic Microwave Background' review), this can be stated as the allowed range for the baryon mass density today, ρ b = (3.9-4.6) × 10 −31 g cm −3 , or as the baryonic fraction of the critical density, Ω b = ρ b /ρ crit ≃ η 10 h −2 /274 = (0.021-0.025)h −2 , where h ≡ H 0 /100 km s −1 Mpc −1 is the present Hubble parameter (see Cosmological Parameters review).The nucleosynthesis chain begins with the formation of deuterium in the process p(n, γ)D. However, photo-dissociation by the high number density of photons delays

show abstract

Electron energy distribution in photolytically pumped lasers

Cited by 10 publications

References 12 publications

Big-Bang Nucleosynthesis

Big-Bang Nucleosynthesis

Electron energy distribution functions and second kind collisions

Big Bang Nucleosynthesis

Contact Info

Product

Resources

About